Non-entropy encoded layer dependency information

ABSTRACT

Systems, methods, and devices for coding multilayer video data are disclosed that may include encoding, decoding, transmitting, or receiving a non-entropy encoded layer dependency information at a position within a video parameter set (VPS) extension prior to syntax elements of the VPS extension that are entropy encoded. The systems, methods, and devices may encode or decode the non-entropy encoded layer dependency information before an entropy encoded syntax element. The systems, methods, and devices may encode or decode video data of one or more of the layers of video data based on the non-entropy encoded layer dependency information. The layer dependency information indicates whether one of the layers is a direct reference layer for another of the layers.

This application claims the benefit of U.S. Provisional Application No.61/809,858, filed Apr. 8, 2013, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

This disclosure relates to coding of parameter sets in video coding.

BACKGROUND

Digital video capabilities can be incorporated into a wide range ofdevices, including digital televisions, digital direct broadcastsystems, wireless broadcast systems, personal digital assistants (PDAs),laptop or desktop computers, tablet computers, e-book readers, digitalcameras, digital recording devices, digital media players, video gamingdevices, video game consoles, cellular or satellite radio telephones,so-called “smart phones,” video teleconferencing devices, videostreaming devices, and the like. Digital video devices implement videocompression techniques, such as those described in the standards definedby MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264 MPEG-4, Part 10, AdvancedVideo Coding (AVC), the High Efficiency Video Coding (HEVC) standard,and extensions of such standards. The video devices may transmit,receive, encode, decode, and/or store digital video information moreefficiently by implementing such video compression techniques.

Video compression techniques perform spatial (intra-picture) predictionand/or temporal (inter-picture) prediction to reduce or removeredundancy inherent in video sequences. For block-based video coding, avideo slice (i.e., a video frame or a portion of a video frame) may bepartitioned into video blocks, which may also be referred to astreeblocks, coding units (CUs) and/or coding nodes. Video blocks in anintra-coded (I) slice of a picture are encoded using spatial predictionwith respect to reference samples in neighboring blocks in the samepicture. Video blocks in an inter-coded (P or B) slice of a picture maybe encoded using spatial prediction with respect to reference samples inneighboring blocks in the same picture or temporal prediction withrespect to reference samples in other reference pictures. Pictures maybe referred to as frames, and reference pictures may be referred to asreference frames.

Spatial or temporal prediction results in a predictive block for a blockto be coded. Residual data represents pixel differences between theoriginal block to be coded and the predictive block. An inter-codedblock is encoded according to a motion vector that points to a block ofreference samples forming the predictive block, and the residual dataindicating the difference between the coded block and the predictiveblock. An intra-coded block is encoded according to an intra-coding modeand the residual data. For further compression, the residual data may betransformed from the pixel domain to a transform domain, resulting inresidual transform coefficients, which then may be quantized. Thequantized transform coefficients, initially arranged in atwo-dimensional array, may be scanned in order to produce aone-dimensional vector of transform coefficients, and entropy coding maybe applied to the transform coefficients to achieve further compression.

SUMMARY

This disclosure relates to techniques for coding parameter sets suchthat more than one output layer set may be coded for one layer set. Inone example, a first output layer set for a layer set and a secondoutput layer set for the layer set may be used to code video data. Forexample, video data may be coded for the first output layer set and forthe second output layer set.

This disclosure relates to techniques for coding parameter sets. Forexample, a video coder may code all profile, tier, and/or levelinformation in the VPS, and profile, tier, level information may beassociate with each output layer set signalled by one profile, tier,level syntax structure, in some examples in a way that it is accessiblewithout entropy decoding. In one example, the disclosure describestechniques for coding profile_tier_level syntax structures in parameterset extension syntax, such as video parameter set (VPS) extensionsyntax, in some examples at a position within the parameter setextension syntax that is accessible without entropy coding (i.e., priorto any entropy-coded syntax elements in the parameter set extension).While in some examples all profile, tier, and/or level information inthe VPS may be accessible without entropy coding, in other examples, areduced amount of entropy coding or some limited entropy coding may berequired for some or all profile, tier, and/or level information in theVPS.

In another example, this disclosure relates to techniques for codinglayer dependency information in multilayer video data in a VPS such thatit is accessible without entropy decoding. Some examples may codemultilayer video data, including transmitting or receiving a non-entropyencoded layer dependency information at a position within a VPSextension prior to syntax elements of parameter set extension syntaxthat are entropy encoded. The technique may include coding video data ofone or more of the layers of video data based on the non-entropy encodedlayer dependency information. The layer dependency information indicateswhether one of the layers is a direct reference layer for another of thelayers.

In another example, this disclosure relates to techniques for codingparameter sets. For example, a video coder may code all profile, tier,and/or level information in the VPS, and profile, tier, levelinformation may be associate with each output layer set signalled by oneprofile, tier, level syntax structure, in some cases in a way that it isaccessible without entropy decoding. While in some examples all profile,tier, and/or level information in the VPS may be accessible withoutentropy coding, in other examples, a reduced amount of entropy coding orsome limited entropy coding may be required for some or all profile,tier, and/or level information in the VPS.

In another example, this disclosure relates to techniques for codingvisual signal information, such as video_format, video_full_range_flag,colour_primaries, transfer_characteristics, matrix_coeffs, per layer inthe VPS.

In another example, this disclosure relates to techniques for SPSsharing by layers of different spatial resolutions, bit depth, or colorformats.

In another example, this disclosure relates to techniques for videocoding such that no timing information is provided in the VideoUsability Information (VUI) of a sequence parameter set (SPS) with layerID (nuh_layer_id) greater than 0.

In another example, this disclosure relates to techniques for videocoding such that no explicit signaling of target output layers isprovided for the default output layer sets.

In another example, this disclosure relates to techniques for avoidingthe signaling of the maximum number of temporal sub-layers that may bepresent in each coded video sequence (CVS) (sps_max_sub_layers_minus1)or whether inter prediction is additionally restricted for CVSs(sps_temporal_id_nesting_flag) in SPSs with layer ID greater than 0.

In another example, this disclosure relates to techniques for, syntaxelement output_layer_set_idx[i] may be changed tooutput_layer_set_idx_minus1[i] in accordance with the techniques of thisdisclosure.

In one example, the disclosure describes a method of decoding multilayervideo data including layers of video data, the method comprisingreceiving a non-entropy encoded layer dependency information at aposition within a video parameter set (VPS) extension prior to syntaxelements of the VPS extension that are entropy encoded, decoding thenon-entropy encoded layer dependency information before an entropyencoded syntax element, and decoding video data of one or more of thelayers of video data based on the non-entropy encoded layer dependencyinformation, wherein the layer dependency information indicates whetherone of the layers is a direct reference layer for another of the layers.

In one example, the disclosure describes a method of encoding multilayervideo data including layers of video data, the method comprisingencoding video data of one or more of the layers of video data based ona non-entropy encoded layer dependency information, wherein a layerdependency information indicates whether one of the layers is a directreference layer for another of the layers, and encoding the non-entropyencoded layer dependency information at a position within a videoparameter set (VPS) extension prior to syntax elements of the VPSextension that are entropy encoded.

In another example, the disclosure describes an apparatus for decodingvideo data comprising a memory configured to store the video data, andone or more processors configured to receive a non-entropy encoded layerdependency information at a position within a video parameter set (VPS)extension prior to syntax elements of the VPS extension that are entropyencoded, decode the non-entropy encoded layer dependency informationbefore an entropy encoded syntax element; and

decode video data of one or more layers of video data based on thenon-entropy encoded layer dependency information, wherein the layerdependency information indicates whether one of the layers is a directreference layer for another of the layers.

In another example, the disclosure describes an apparatus for encodingvideo data comprising a memory configured to store the video data, andone or more processors configured to encode video data of one or morelayers of video data based on a non-entropy encoded layer dependencyinformation, wherein a layer dependency information indicates whetherone of the layers is a direct reference layer for another of the layers,and encode the non-entropy encoded layer dependency information at aposition within a video parameter set (VPS) extension prior to syntaxelements of the VPS extension that are entropy encoded.

In another example, the disclosure describes an apparatus for decodingmultilayer video data including layers of video data comprising meansfor receiving a non-entropy encoded layer dependency information at aposition within a video parameter set (VPS) extension prior to syntaxelements of the VPS extension that are entropy encoded, means fordecoding the non-entropy encoded layer dependency information before anentropy encoded syntax element, and means for decoding video data of oneor more of the layers of video data based on the non-entropy encodedlayer dependency information, wherein the layer dependency informationindicates whether one of the layers is a direct reference layer foranother of the layers.

In another example, the disclosure describes a computer-readable storagemedium. The computer-readable storage medium having stored thereoninstructions that upon execution cause one or more processors to receivea non-entropy encoded layer dependency information at a position withina video parameter set (VPS) extension prior to syntax elements of theVPS extension that are entropy encoded, decode the non-entropy encodedlayer dependency information before an entropy encoded syntax element,and decode video data of one or more layers of video data based on thenon-entropy encoded layer dependency information, wherein the layerdependency information indicates whether one of the layers is a directreference layer for another of the layers.

The details of one or more examples are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example video encoding anddecoding system that may utilize the techniques described in thisdisclosure.

FIG. 2 is a block diagram illustrating an example video encoder that mayimplement the techniques described in this disclosure.

FIG. 3 is a block diagram illustrating an example video decoder that mayimplement the techniques described in this disclosure.

FIG. 4 is a flowchart illustrating an example method for decoding videodata in accordance with the systems and methods described herein.

FIG. 5 is a flowchart illustrating another example method for encodingvideo data in accordance with the systems and methods described herein.

FIG. 6 is a flowchart illustrating an example method for decoding videodata in accordance with the systems and methods described herein.

FIG. 7 is a flowchart illustrating an example method for encoding videodata in accordance with the systems and methods described herein.

FIG. 8 is a flowchart illustrating an example method for decoding videodata in accordance with the systems and methods described herein.

FIG. 9 is a flowchart illustrating an example method for encoding videodata in accordance with the systems and methods described herein.

FIG. 10 is a flowchart illustrating an example method for decoding videodata in accordance with the systems and methods described herein.

FIG. 11 is a flowchart illustrating an example method for encoding videodata in accordance with the systems and methods described herein.

FIG. 12 is a flowchart illustrating an example method for decoding videodata in accordance with the systems and methods described herein.

FIG. 13 is a flowchart illustrating an example method for encoding videodata in accordance with the systems and methods described herein.

DETAILED DESCRIPTION

This disclosure is generally related to the field of video coding andcompression. As one example, the disclosure is related to the highefficiency video coding (HEVC) standard currently under development. Theterm “coding” refers to encoding and decoding, and the techniques mayapply to encoding, decoding or both encoding and decoding. As describedin more detail, the techniques may be related to intra-coding (e.g.,intra-prediction) in which a block within a picture is predicted withrespect to another block or blocks in the same picture (i.e., spatialprediction).

In previous video coding systems, accessing of the profile, tier andlevel for layer sets require entropy decoding. Similarly, the layerdependency information is not accessible without entropy decoding.Signaling of an output layer set may also be problematic andinefficient.

One example of the systems, methods, and devices described hereinprovides for a set of profile_tier_level( ) syntax structures to besignalled in parameter set extension syntax, such as video parameter set(VPS) extension syntax, potentially at a position within the extensionsyntax that is accessible without entropy coding, (e.g., prior toentropy-coded elements in the extension syntax) and/or with some reducedor limited entropy coding. The VPS extension syntax will be describedthroughout this disclosure for purposes of example. In an example, theVPS is a syntax structure containing syntax elements that apply to zeroor more entire coded video sequences (CVSs) as determined by the contentof a syntax element found in the SPS referred to by a syntax elementfound in the PPS referred to by a syntax element found in each slicesegment header. In an example, a CVS is a sequence of access units thatinclude, in decoding order, of an IRAP access unit with NoRaslOutputFlagequal to 1, followed by zero or more access units that are not IRAPaccess units with NoRaslOutputFlag equal to 1, including all subsequentaccess units up to but not including any subsequent access unit that isan IRAP access unit with NoRaslOutputFlag equal to 1. Furthermore, aprofile_tier_level( ) syntax structure may be associated with an outputlayer set instead of a layer set, because a layer set may correspond tomore than one output layer set, and different output layer setscorresponding to one layer set may comply to different levels.

The profile_tier_level( ) syntax structure is a syntax structure thatprovides syntax information related to profiles, tiers, and levels.Profiles, tiers, and levels specify different points of conformance forimplementing the HEVC standard or an HEVC extension standard such thatit is interoperable across various applications that may have similarfunctional requirements. In some examples, a profile may define a set ofcoding tools or algorithms that may be used in generating a conformingbitstream. In some examples, a tier and a level may place constraints onsome of the parameters of the bitstream. In some examples, theseparameters may correspond to decoder processing load and decoder memorycapabilities. The level information may establish restrictions onprocessing of data. For example, the level information may includemaximum sample rate, maximum picture size, maximum bit rate, minimumcompression ratio. The level information may also include capacities ofthe decoded picture buffer (DPB) and the coded picture buffer (CPB). TheCPB holds compressed data prior to its decoding for data flow managementpurposes. The DPB holds decoded picture data.

Another example of the systems, methods, and devices described hereinprovides for coding multilayer video data including layers of videodata. These systems, methods, and devices may include transmitting orreceiving a non-entropy encoded layer dependency information at aposition within a parameter set extension syntax, such as VPS extensionsyntax, prior to syntax elements of the extension that are entropyencoded. Additionally, the systems, methods, and devices may decodevideo data of one or more of the layers of video data based on thenon-entropy encoded layer dependency information. The layer dependencyinformation indicates whether one of the layers is a direct referencelayer for another of the layers. Again, the VPS extension syntax will bedescribed throughout this disclosure for purposes of example.

As is described in greater detail below, in one example, more than oneoutput layer set may be signalled for one layer set. For example, asdescribed herein, the syntax element output_layer_flag[lsIdx][j] may bechanged to output_layer_flag[i][j], and related semantics are changedaccordingly.

As is described in greater detail below, in another example, profile,tier, and level information may be signalled in the VPS in a way that itis accessible without entropy decoding. This is illustrated in one ormore of the tables below with parameters that have descriptors otherthan ue(v) (ue(v) indicating entropy coding). For example, thedescriptors may indicate fixed length coding, e.g., u(n), where n is aninteger 1 or greater.

As is described in greater detail below, in another example, the layerdependency information may be signalled in the VPS in a way that it isaccessible without entropy. This is illustrated in one or more of thetables below with parameters that have descriptors other than ue(v). Forexample, the descriptors may indicate fixed length coding, e.g., u(n),where n is an integer 1 or greater.

As is described in greater detail below, in another example, arepresentation format may be signalled in the VPS, potentially in a waythat it is accessible without entropy decoding or some reduced orlimited entropy coding. For example, representation format parameterssuch as chroma_format_vps_idc, separate_colour_plane_vps_flag,pic_width_vps_in_luma_samples, pic_height_vps_in_luma_samples,bit_depth_vps_luma_minus8, and bit_depth_vps_chroma_minus8 are signalledin the VPS, and not entropy coded in some examples. This is illustratedin one or more of the tables below with these parameters havingdescriptors other than ue(v). The representation format parameters mayhave descriptors that indicate that the particular parameter is fixedlength coding, e.g., u(n), where n is an integer 1 or greater. In somecases the “_vps” has been dropped from various parameter names, e.g.,chroma_format_vps_idc may also be referred to as chroma_format_idc,separate_colour_plane_vps_flag as separate_colour_plane_flag,pic_width_vps_in_luma_samples as pic_width_in_luma_samples,pic_heigh_vps_in_luma_samples as pic_height_in_luma_samples,bit_depth_vps_luma_minus8 as bit_depth_luma_minus8, andbit_depth_vps_chroma_minus8 as bit_depth_vps_chroma_minus8, as well asother parameters.

As is described in greater detail below, in another example, visualsignal information such as video_format, video_full_range_flag,colour_primaries, transfer_characteristics, or matrix_coeffs may besignalled per layer in the VPS. As described herein the visual signalinformation such as video_format, video_full_range_flag,colour_primaries, transfer_characteristics, matrix_coeffs may be asubset of the Video Usability Information (VUI) parameters, as specifiedin Annex E of the HEVC standard, for example. The VUI, and hence thevisual signal information, is in the VPS and may be signalled per layerin the VPS.

As is described in greater detail below, in another example, sequenceparameter set (SPS) sharing may be performed by layers with differentspatial resolutions, bit depth, or color formats. In an example, the SPSis a syntax structure containing syntax elements that apply to a layerin zero or more entire CVSs as determined by the content of a syntaxelement found in the PPS referred to by a syntax element found in eachslice segment header. In some examples, a method of decoding multilayervideo data may include receiving a video parameter set and a firstsequence parameter set. The method may also include receiving a firstlayer that refers to the first sequence parameter set, receiving asecond layer that has a different value of at least one of a spatialresolution, a bit depth, and a color format than the first layer, andthat refers to the first sequence parameter set. Furthermore, theexample method may include decoding video data of the first and secondlayers based on information from the video parameter set and the firstsequence parameter set.

As is described in greater detail below, in another example, no timinginformation is coded in the VUI of SPSs with layer ID (nuh_layer_id)greater than 0. In some examples, for a layer that refers to an SPS withlayer ID greater than 0, the timing information signalled in the VPS isused.

As is described in greater detail below, in another example, no explicitsignaling of target output layers is used for default output layer sets.For example, because having multiple_output_layer_sets_in_layer_set_flagequal to 0 specifies that only one output layer set is specified by theVPS for each layer set, with the highest layer being the only targetoutput layer, no explicit signaling of target output layers for thedefault output layer sets is needed. For example, there is no need tosignal which layers are to be output whenmultiple_output_layer_sets_in_layer_set_flag is equal to 0 because thereis only one output layer set for each layer set and the highest layer isthe only target output layer.

As is described in greater detail below, in another example, thesps_max_sub_layers_minus1 and sps_temporal_id_nesting_flag are notsignalled in the SPS. In some cases, this signaling does not occur inthe SPS when nuh_layer_id_(—)>0.

As is described in greater detail below, in another example, the syntaxelement output_layer_set_idx[i] may be changed tooutput_layer_set_idx_minus1[i]. This is because the syntax elementlayer_id_included_flag[i][j] used for output_layer_set_idx[i] equal to 0is for layer set 0, while for layer set 0 layer_id_included_flag[i][j]is not defined. Additionally, the target output layer for layer set 0 isalways layer 0 (the base layer).

Various examples above may include aspects with various data,parameters, etc. that are not entropy coded. Because of this, the data,parameters, etc. may be accessible to devices without an entropy coderto perform entropy coding. For example, in some cases a Media AwareNetwork Entities (MANEs) may not have an entropy coding device, butwould generally be able to code (e.g., decode) non-entropy codedinformation such as data, parameters, etc.

A recent draft of the HEVC standard, referred to as “HEVC Working Draft10” or “WD10,” is described in document JCTVC-L1003v34, Bross et al.,“High efficiency video coding (HEVC) text specification draft 10 (forFDIS & Last Call),” Joint Collaborative Team on Video Coding (JCT-VC) ofITU-T SG16 WP3 and ISO/IEC JTC1/SC29/WG11, 12th Meeting: Geneva, CH,14-23 Jan. 2013, which, as of Oct. 15, 2013, is downloadable from:http://phenix.int-evry.fr/jct/doc_end_user/documents12_Geneva/wg11/JCTVC-L1003-v34.zip

Another recent working Draft (WD) of HEVC, referred to as “HEVC WorkingDraft 6” or “WD6,” is described in document JCTVC-H1003, Bross et al.,“High-Efficiency Video Coding (HEVC) text specification draft 6,” JointCollaborative Team on Video Coding (JCT-VC) of ITU-T SG16 WP3 andISO/IEC JTC1/SC29/WG11, 8th Meeting: San Jose, Calif., USA, February2012, which as of Oct. 15, 2013 is downloadable from:http://phenix.int-evry.fr/jct/doc_end_user/documents/8_San%20Jose/wg11JCTVC-H1003-v22.zip

Another recent working Draft (WD) of HEVC, referred to as “HEVC WorkingDraft 8” or “WD8,” is described in document JCTVC-J1003, Bross et al.,“High-Efficiency Video Coding (HEVC) text specification draft 8,” JointCollaborative Team on Video Coding (JCT-VC) of ITU-T SG16 WP3 andISO/IEC JTC1/SC29/WG11, 10th Meeting: Stockholm, SE, 11-20 Jul. 2012,which as of Oct. 15, 2013 is downloadable from:http://phenix.int-evry.fr/jct/doc_end_user/documents/10_Stockholm/wg11/JCTVC-J1003-v8.zip

HEVC Range Extensions are described in document JCTVC-N1005_v3, Flynn etal., “High Efficiency Video Coding (HEVC) Range Extensions textspecification: Draft 4,” Joint Collaborative Team on Video Coding(JCT-VC) of ITU-T SG16 WP3 and ISO/IEC JTC1/SC29/WG11, 13th Meeting:Incheon, KR, 18-26 Apr. 2013, which as of Oct. 15, 2013 is downloadablefrom:http://phenix.it-sudparis.eu/jct/doc_end_user/current_document.php?id=8139.

FIG. 1 is a block diagram illustrating an example video encoding anddecoding system 10 that may utilize the techniques described in thisdisclosure. As illustrated in FIG. 1, system 10 includes a video encoder20 that generates encoded video data to be decoded at a later time by avideo decoder 30. Source device 12 and destination device 14 maycomprise any of a wide range of devices, including desktop computers,notebook (i.e., laptop) computers, tablet computers, set-top boxes,telephone handsets such as so-called “smart” phones, so-called “smart”pads, televisions, cameras, display devices, digital media players,video gaming consoles, video streaming device, or the like. In somecases, source device 12 and destination device 14 may be equipped forwireless communication.

Destination device 14 may receive the encoded video data to be decodedvia a link 16. Link 16 may comprise any type of medium or device capableof moving the encoded video data from video encoder 20 to video decoder30. In one example, link 16 may comprise a communication medium toenable video encoder 20 to transmit encoded video data directly to videodecoder 30 in real-time. The encoded video data may be modulatedaccording to a communication standard, such as a wireless communicationprotocol, and transmitted to destination device 14. The communicationmedium may comprise any wireless or wired communication medium, such asa radio frequency (RF) spectrum or one or more physical transmissionlines. The communication medium may form part of a packet-based network,such as a local area network, a wide-area network, or a global networksuch as the Internet. The communication medium may include routers,switches, base stations, or any other equipment that may be useful tofacilitate communication from source device 12 to destination device 14.

Alternatively, encoded data may be output from output interface 22 to astorage device 34. Similarly, input interface 28 may access encoded datafrom storage device 34. Storage device 34 may include any of a varietyof distributed or locally accessed data storage media such as a harddrive, Blu-ray discs, DVDs, CD-ROMs, flash memory, volatile ornon-volatile memory, or any other suitable digital storage media forstoring encoded video data. In a further example, storage device 34 maycorrespond to a file server or another intermediate storage device thatmay hold the encoded video generated by video encoder 20. Destinationdevice 14 may access stored video data from storage device 34 viastreaming or download via input interface 28. The file server may be anytype of server capable of storing encoded video data and transmittingthat encoded video data to the video decoder 30. Example file serversinclude a web server (e.g., for a website), a File Transfer Protocal(FTP) server, network attached storage (NAS) devices, or a local diskdrive. Video decoder 30 may access the encoded video data through anystandard data connection, including an Internet connection. This mayinclude a wireless channel (e.g., a Wi-Fi connection), a wiredconnection (e.g., DSL, cable modem, etc.), or a combination of both thatis suitable for accessing encoded video data stored on a file server.The transmission of encoded video data from storage device 34 may be astreaming transmission, a download transmission, or a combination ofboth.

The techniques of this disclosure are not necessarily limited towireless applications or settings. The techniques may be applied tovideo coding in support of any of a variety of multimedia applications,such as over-the-air television broadcasts, cable televisiontransmissions, satellite television transmissions, streaming videotransmissions, e.g., via the Internet, encoding of digital video forstorage on a data storage medium, decoding of digital video stored on adata storage medium, or other applications. In some examples, system 10may be configured to support one-way or two-way video transmission tosupport applications such as video streaming, video playback, videobroadcasting, and/or video telephony.

In the example of FIG. 1, source device 12 includes a video source 18,video encoder 20 and an output interface 22. In some cases, outputinterface 22 may include a modulator/demodulator (modem) and/or atransmitter. Video source 18 may include a source such as a videocapture device, e.g., a video camera, a video archive containingpreviously captured video, a video feed interface to receive video froma video content provider, and/or a computer graphics system forgenerating computer graphics data as the source video, or a combinationof such sources. As one example, if video source 18 is a video camera,source device 12 and destination device 14 may form so-called cameraphones or video phones. However, the techniques described in thisdisclosure may be applicable to video coding in general, and may beapplied to wireless and/or wired applications.

Video encoder 20 encodes the captured, pre-captured, orcomputer-generated video received from video source 18. The captured,pre-captured, or computer-generated video may be formatted according toany of the sample formats described above including the 4:2:0, 4:2:2 or4:4:4 sample formats. Video encoder 20 may perform video coding on videoformatted according to any of the 4:2:0, 4:2:2 or 4:4:4 sample formats.In some cases, video encoder 20 may up sample or down sample thecaptured, pre-captured, or computer-generated video as part of thecoding process. For example, captured video may be formatted accordingto the 4:4:4 sample format, video encoder 20 may down sample capturedvideo to the 4:2:2 format and perform video encoding on the down sampledvideo. The encoded video data may be transmitted directly to destinationdevice 14 via output interface 22 of source device 12. The encoded videodata may also (or alternatively) be stored onto storage device 34 forlater access by destination device 14 or other devices, for decodingand/or playback.

Destination device 14 includes an input interface 28, a video decoder30, and a display device 32. In some cases, input interface 28 mayinclude a receiver and/or a modem. Input interface 28 of destinationdevice 14 receives the encoded video data over link 16. The encodedvideo data communicated over link 16, or provided on storage device 34,may include a variety of syntax elements generated by video encoder 20for use by a video decoder, such as video decoder 30, in decoding thevideo data. Such syntax elements may be included with the encoded videodata transmitted on a communication medium, stored on a storage medium,or stored on a file server.

Display device 32 may be integrated with, or external to, destinationdevice 14. In some examples, destination device 14 may include anintegrated display device and also be configured to interface with anexternal display device. In other examples, destination device 14 may bea display device. In general, display device 32 displays the decodedvideo data to a user, and may comprise any of a variety of displaydevices such as a liquid crystal display (LCD), a plasma display, anorganic light emitting diode (OLED) display, or another type of displaydevice.

Video encoder 20 and video decoder 30 may operate according to a videocompression standard, such as the High Efficiency Video Coding (HEVC)standard presently under development, and may generally conform to thecurrent HEVC Test Model (HM) or a future HM.

Alternatively, video encoder 20 and video decoder 30 may operateaccording to other proprietary or industry standards, such as the ITU-TH.264 standard, alternatively referred to as MPEG-4, Part 10, AdvancedVideo Coding (AVC), or revisions or extensions of such standards. Thetechniques of this disclosure are described as applicable to HEVCextensions, but are not necessarily limited to any particular codingstandard. Other examples of video compression standards include MPEG-2and ITU-T H.263.

Although not shown in FIG. 1, in some aspects, video encoder 20 andvideo decoder 30 may each be integrated with an audio encoder anddecoder, and may include appropriate MUX-DEMUX units, or other hardwareand software, to handle encoding of both audio and video in a commondata stream or separate data streams. If applicable, in some examples,MUX-DEMUX units may conform to the ITU H.223 multiplexer protocol, orother protocols such as the user datagram protocol (UDP).

Video encoder 20 and video decoder 30 each may be implemented as any ofa variety of suitable encoder circuitry, such as one or moremicroprocessors, digital signal processors (DSPs), application specificintegrated circuits (ASICs), field programmable gate arrays (FPGAs),discrete logic, software, hardware, firmware or any combinationsthereof. When the techniques are implemented partially in software, adevice may store instructions for the software in a suitable,non-transitory computer-readable medium and execute the instructions inhardware using one or more processors to perform the techniques of thisdisclosure. Each of video encoder 20 and video decoder 30 may beincluded in one or more encoders or decoders, either of which may beintegrated as part of a combined encoderdecoder (CODEC) in a respectivedevice.

In the illustrated example of FIG. 1, a video coder, such as a videoencoder 20 or a video decoder 30 may transmit or receive a non-entropyencoded set of profile, tier, and level syntax structures. For example,video encoder 20 may transmit a non-entropy encoded set of profile,tier, and level syntax structures and video decoder 30 may receive anon-entropy encoded set of profile, tier, and level syntax structures,e.g., sent from video encoder 20.

The non-entropy encoded set of profile, tier, and level syntaxstructures may be at a position within a VPS extension prior to othersyntax elements of the VPS extension that are entropy encoded. The videocoder (e.g., video encoder 20 or video decoder 30) may refer to one ofthe profile, tier, and level syntax structures for each of a pluralityof output layer sets and decode video data of one of the output layersets based on information from the profile, tier, and level syntaxstructure referred to for the output layer set. For example, videoencoder 20 may refer to one of the profile, tier, and level syntaxstructures for each of a plurality of output layer sets and encode videodata of one of the output layer sets based on information from theprofile, tier, and level syntax structure referred to for the outputlayer set. Video decoder 30 may refer to one of the profile, tier, andlevel syntax structures for each of a plurality of output layer sets anddecode video data of one of the output layer sets based on informationfrom the profile, tier, and level syntax structure referred to for theoutput layer set.

In some examples, the video coder may further transmit or receive asequence parameter set (SPS) with a nuh_layer_id equal to 0, wherein theSPS includes a profile, tier, and level syntax structure for a layer ofvideo data. The nuh_layer_id may be used to indicate a particular layer.A layer may be a set of video coding layer (VCL) network abstractionlayer (NAL) units that all have a particular value of nuh_layer_id andthe associated non-VCL NAL units, or one of a set of syntacticalstructures having a hierarchical relationship. nuh_layer_id shall beequal to 0 in a bitstream containing only one layer. Other values ofnuh_layer_id may appear in bitstreams containing multiple layers. In anexample, a NAL unit is a syntax structure containing an indication ofthe type of data to follow and bytes containing that data in the form ofa raw byte sequence payload (RBSP) interspersed as necessary withemulation prevention bytes. In an example, an RBSP is a syntax structurecontaining an integer number of bytes that is encapsulated in a NAL unitand that is either empty or has the form of a string of data bitscontaining syntax elements followed by an RBSP stop bit and zero or moresubsequent bits equal to 0.

Video encoder 20 may transmit an SPS with a nuh_layer_id equal to 0,wherein the SPS includes the profile, tier, and level syntax structurefor a layer of video data. Video decoder 30 may receive the SPS with anuh_layer_id equal to 0, wherein the SPS includes a profile, tier, andlevel syntax structure for a layer of video data.

In some examples, when a layer with nuh_layer_id greater than 0 refersto the SPS, the video decoder might not decode video data of the layerwith nuh_layer_id greater than 0 using the profile, tier, and levelsyntax structure of the SPS. Some examples may link the profile, tier,and level syntax structures to respective ones of the output layer sets.Accordingly, one or more specific profile, tier, and level syntaxstructures may be connected to one or more specific output layer setssuch that the one or more specific profile, tier, and level syntaxstructures may be used to encode and/or decode one or more specificoutput layer sets. Linking may include identifying each of the outputlayer sets to which each of the profile, tier and level syntaxstructures is linked based on a syntax element representing an index tothe profile, tier, and level syntax structures. Decoding video data mayinclude decoding video data of one or more of the output layer setsbased on information from the profile, tier, and level syntax structureslinked to the respective output layer sets.

In an example that includes multiple layers, a bitstream of all of thelayers may be split into multiple compliant bitstreams, e.g., onebitstream for each layer set. Each of these multiple compliantbitstreams may be referred to as a layer set. The layer set may includea reference to the particular layer and any reference layers which thatparticular layer is dependent upon for decoding. This assumes there arereference layers that the particular layer depends on. Accordingly, alayer set is a compliant bitstream that may include NAL units associatedwith the particular layer and NAL units for any reference layersrequired for decoding the particular layer.

An output layer set is a layer set for which the list of target outputlayers is specified. For a layer set, the list of target output layersis not specified. The output layer set may be for one or more particularlayers that are intended to be output for display. In some examples,more than one output layer set may be signalled for one layer set.

In some examples, the video coder (e.g., video encoder 20 or videodecoder 30) may transmit or receive, as applicable, an output layer flag[i] [j] that, when equal to 1, specifies that a j-th layer in the layerset is a target output layer of an i-th output layer set, and, whenequal to 0, specifies that the j-th layer in the layer set is not thetarget output layer of the i-th output layer set. For examples, videoencoder 20 may transmit an output layer flag [i] [j] that, when equal to1, specifies that a j-th layer in the layer set is a target output layerof an i-th output layer set, and, when equal to 0, specifies that thej-th layer in the layer set is not the target output layer of the i-thoutput layer set. Video decoder 30 may transmit an output layer flag [i][j] that, when equal to 1, specifies that a j-th layer in the layer setis a target output layer of an i-th output layer set, and, when equal to0, specifies that the j-th layer in the layer set is not the targetoutput layer of the i-th output layer set.

The video coder (e.g., video encoder 20 or video decoder 30) may alsogenerate the output layer set based on the output layer flag [i] [j] byspecifying the layers corresponding to output layer flag [i] [j] equalto 1 as the associated list of target output layers. For example, videoencoder 20 may encode the output layer set based on the output layerflag [i] [j]. Video decoder 30 may decode the output layer set based onthe output layer flag [i] [j]. In the illustrated example of FIG. 1, avideo coder, such as a video encoder 20 or a video decoder 30 may codemultilayer video data including layers of video data.

The video coder (e.g., video encoder 20 or video decoder 30) maytransmit or receive a non-entropy encoded layer dependency informationat a position within a VPS extension prior to syntax elements of the VPSextension that are entropy encoded. This can allow the layer dependencyinformation to be encoded or decoded by devices that do not include anentropy coder, e.g., such as a MANE. Additionally, it may also allow thelayer dependency information to be coded sooner. For example, the layerdependency information may be decoder earlier in the decoding process.For example, video encoder 20 may transmit a non-entropy encoded layerdependency information at a position within a VPS extension prior tosyntax elements of the VPS extension that are entropy encoded. Videodecoder 30 may receive a non-entropy encoded layer dependencyinformation at a position within a VPS extension prior to syntaxelements of the VPS extension that are entropy encoded.

The video coder (e.g., video encoder 20 or video decoder 30) may codevideo data of one or more of the layers of video data based on thenon-entropy encoded layer dependency information. For example, videoencoder 20 may encode video data of one or more of the layers of videodata based on the non-entropy encoded layer dependency information.Video decoder 30 may encode video data of one or more of the layers ofvideo data based on the non-entropy encoded layer dependencyinformation. The layer dependency information indicates whether one ofthe layers is a direct reference layer for another of the layers.

In some examples, the layer dependency information includes adirect_dependency_flag[i][j] that, when equal to 0, specifies that alayer with index j is not a direct reference layer for a layer withindex I, and when equal to 1, specifies that the layer with index j maybe a direct reference layer for the layer with index i.

One example of the systems, methods, and devices described hereinprovides for a set of profile_tier_level( ) syntax structures to besignalled in VPS extension syntax. In some examples, the set ofprofile_tier_level( ) syntax structures is signalled in VPS extensionsyntax at a position within the VPS extension syntax that is accessiblewithout entropy coding, i.e., prior to entropy-coded elements in the VPSextension syntax.

Some examples provide profile, tier, and level syntax structures beforeentropy coded elements of the VPS extension syntax. These syntaxstructures can be linked to output layer sets. In some examples, thesyntax element vps_num_layer_sets_minus1 plus 1 specifies the number oflayer sets that are specified by the VPS. A layer set may be a setincluding a layer and any (zero or more) other layers on which the layeris dependent. For example, a layer set for layer 2 in scalable videocoding may include layer 0, layer 1 and layer 2. For each layer set, oneor more output layer sets may be specified. Each output layer set isdesignated to have a profile, level and tier.

In one example of the disclosure, a portion of the VPS syntax may be asfollows in Table 1:

TABLE 1 An example portion of the VPS syntax video_parameter_set_rbsp( ){ Descriptor  vps_video_parameter_set_id u(4)  vps_reserved_three_2bitsu(2)  vps_max_layers_minus1 u(6)  vps_max_sub_layers_minus1 u(3) vps_temporal_id_nesting_flag u(1)  vps_extension_offset//vps_reserved_0xffff_16bits u(16)  profile_tier_level( 1,vps_max_sub_layers_minus1 )  vps_sub_layer_ordering_info_present_flagu(1)  for( i = ( vps_sub_layer_ordering_info_present_flag ? 0 :vps_max_sub_layers_minus1 );  i <= vps_max_sub_layers_minus1; i++ ) {  vps_max_dec_pic_buffering_minus1[ i ] ue(v)  vps_max_num_reorder_pics[ i ] ue(v)   vps_max_latency_increase_plus1[i ] ue(v)  }  vps_max_layer_id u(6)  vps_num_layer_sets_minus1 ue(v) for( i = 1; i <= vps_num_layer_sets_minus1; i++ )   for( j = 0; j <=vps_max_layer_id; j++ )  layer_id_included_flag[ i ][ j ] u(1) vps_timing_info_present_flag u(1)  if( vps_timing_info_present_flag ) {  vps_num_units_in_tick u(32)   vps_time_scale u(32) vps_poc_proportional_to_timing_flag u(1)  if(vps_poc_proportional_to_timing_flag )  vps_num_ticks_poc_diff_one_minus1 ue(v)   vps_num_hrd_parameters ue(v)

As illustrated above in the example of Table 1,vps_num_layer_sets_minus1 is entropy coded, as indicated by the ue(v)descriptor, in the VPS, and there are other entropy coded syntaxelements before vps_num_layer_sets_minus1 in the VPS. In some examples,entropy decoding may be undesirable. This may be particularly true forintermediate network devices that may perform splicing or streamadaptation (e.g., temporal rate, quality, spatial adaptation). A decoder(e.g., video decoder 30) will generally have an entropy decoder. In manycases, however, it may be desirable for an intermediate network deviceto not have an entropy decoder. This simplifies the intermediate device,which may decrease cost and power consumption in some cases. Inaddition, in either case, it may be desirable to quickly access profile,tier, and level information without having to perform entropy decoding.

To avoid entropy decoding the profile, level and tier syntax structures(profile_tier_level( ) syntax), in some examples, this disclosureproposes presenting the profile, level and tier syntax structures beforeany entropy-coded elements in the VPS extension syntax, and accessiblewithout parsing the entropy-coded vps_num_layer_sets_minus1 syntaxelement. In some cases, extensions may be developed for video codingstandards, such as the HEVC video coding standards. These extensions mayprovide additional functionality not provided by or not required by thevideo coding standards. An extension syntax is a syntax for one of theseextensions to a video coding standard. For example, the VPS extensionsyntax may include the syntax of messages used for an extension to theHEVC video coding standards. Previously, it appears that these would beaccessed as each layer is accessed. Now, a system, method, or deviceimplementing one or more of the concepts described herein may access allof them up front, and then link them later.

TABLE 2 Example syntax in the VPS extension vps_num_profile_tier_level_minus1 u(6)  for( i = 1; i <=vps_num_profile_tier_level_minus1; i++ ) {   vps_profile_present_flag[ i] u(1)   if( !vps_profile_present_flag[ i ] )    profile_ref_minus1[ i ]u(6)   profile_tier_level( vps_profile_present_flag[ i ],vps_max_sub_layers_minus1 )  }

As used in Table 2, vps_num_profile_tier_level_minus1 plus 1 specifiesthe number of profile_tier_level( ) syntax structures in the VPS. Avps_profile_present_flag[i] equal to 1 specifies that the profile andtier information is present in the i-th profile_tier_level( ) syntaxstructure. A vps_profile_present_flag[lsIdx] equal to 0 specifies thatprofile and tier information is not present in the i-thprofile_tier_level( ) syntax structure and may be inferred for the i-thprofile_tier_level( ) syntax structure.

The syntax element profile_ref_minus1[i] specifies that the profile andtier information for the i-th profile_tier_level( ) syntax structure maybe inferred to be equal to the profile and tier information for the(profile_ref_minus1[i]+1)-th profile_tier_level( ) syntax structure. Thevalue of profile_ref_minus1[i]+1 may be less than i.

As illustrated in Table 2, in the syntax above, the decoder orintermediate network device loops through a set of profile_tier_level () syntax structures to access them before parsing elements of the syntaxfor which entropy coding is required (later in the VPS extensionsyntax). These syntax structures may also be linked to correspondinglayer sets with another looping process. In particular,profile_level_tier_idx[i] specifies the index, into the set ofprofile_tier_level( ) syntax structures in the VPS, of theprofile_tier_level( ) syntax structure that applies to i-th output layerset.

For another example aspect, systems, methods, and devices implementingone or more examples described herein may useoutput_layer_set_idx_minus1[i] to indicate the index of the layer setfor layers above layer 0 (the base layer).

The output_layer_set_idx_minus1[i] plus 1 specifies the index (1sIdx) ofthe layer set for the i-th output layer set. In an example, the value ofoutput_layer_set_idx_minus1[i] may be in the range of 0 tovps_num_layer_sets_minus1−1, inclusive. The length of theoutput_layer_set_idx_minus1[i] syntax element is Ceil(Log2(vps_num_layer_sets_minus1)) bits.

Another example of the systems, methods, and devices described hereinprovides for coding multilayer video data including layers of videodata. These systems, methods, and devices may be configured to performoperations including transmitting or receiving a non-entropy encodedlayer dependency information at a position within a VPS extension priorto syntax elements of the VPS extension that are entropy encoded.Additionally, the systems, methods, and devices may decode video data ofone or more of the layers of video data based on the non-entropy encodedlayer dependency information. The layer dependency information indicateswhether one of the layers is a direct reference layer for another of thelayers.

According to one example, a video coder, such as video encoder 20 orvideo decoder 30 may code more than one output layer set for one layerset in accordance with the techniques of this disclosure. For example,video encoder 20 may encode more than one output layer set for one layerset. The encoded output layer sets may be signalled, transmitted orotherwise transferred by output interface 22 through link 16 or usingstorage device 34 and received by input interface 28. The encoded outputlayer sets may be decoded by video decoder 30.

According to another example, a video coder, such as video encoder 20 orvideo decoder 30 may code all profile, tier, and/or level information inthe VPS, potentially in a way that it is accessible without entropydecoding in accordance with the techniques of this disclosure. Forexample, video encoder 20 may encode all profile, tier, levelinformation in the VPS, potentially in a way that it is potentiallyaccessible without entropy decoding, i.e., without entropy encoding theprofile, tier, and/or level information. The encoded profile, tier,and/or level information in the VPS may be signalled, transmitted, orotherwise transferred by output interface 22 through link 16 or usingstorage device 34 and received by input interface 28. The encodedprofile, tier, and/or level information in the VPS may be decoded byvideo decoder 30, which may be a device that does not include an entropydecoder, such as a MANE. Some examples may use reduced or limitedentropy encoding for the profile, tier, level information in the VPS.For example, perhaps some profile, tier, level information in the VPS isentropy encoded while other profile, tier, level information in the VPSis not entropy encoded.

According to another example, a video coder, such as video encoder 20 orvideo decoder 30 may code layer dependency information in the VPS suchthat it is accessible without entropy decoding in accordance with thetechniques of this disclosure. For example, video encoder 20 may encodelayer dependency information in the VPS such that it is accessiblewithout entropy decoding, i.e., without entropy encoding the layerdependency information. The encoded layer dependency information in theVPS may be signalled, transmitted, or otherwise transferred by outputinterface 22 through link 16 or using storage device 34 and received byinput interface 28. The encoded layer dependency information in the VPSmay be decoded by video decoder 30, which may be a device that does notinclude an entropy decoder, such as a MANE.

According to another example, a video coder, such as video encoder 20 orvideo decoder 30 may code representation format in the VPS, potentiallyin a way that it is accessible without entropy decoding in accordancewith the techniques of this disclosure, and each layer may be associatedwith a particular representation format. For example, video encoder 20may encode representation format in the VPS, potentially in a way thatit is accessible without entropy decoding, i.e., without entropyencoding the representation format in the VPS. The encodedrepresentation format in the VPS may be signalled, transmitted, orotherwise transferred by output interface 22 through link 16 or usingstorage device 34 and received by input interface 28. The encodedrepresentation format in the VPS may be decoded by video decoder 30,which may be a device that does not include an entropy decoder, such asa MANE. Some examples may use reduced or limited entropy decoding forthe profile, tier, level information in the VPS. For example, perhapssome profile, tier, level information in the VPS is entropy decodedwhile other profile, tier, level information in the VPS is not entropydecoded (e.g., because some profile, tier, level information in the VPSwas entropy encoded while other profile, tier, level information in theVPS was not entropy encoded).

According to another example, a video coder, such as video encoder 20 orvideo decoder 30 may code visual signal information (video_format,video_full_range_flag, colour_primaries, transfer_characteristics,matrix_coeffs) per layer in the VPS in accordance with the techniques ofthis disclosure. For example, video encoder 20 may encode the visualsignal information per layer in the VPS. The encoded visual signalinformation may be signalled, transmitted, or otherwise transferred byoutput interface 22 through link 16 or using storage device 34 andreceived by input interface 28. The encoded visual signal informationper layer in the VPS may be decoded by video decoder 30. In someexamples, the video_format parameter indicates a format of arepresentation of pictures to be coded. The video_full_range_flagparameter indicates the black level and range of the luma and chromasignals. The colour_primaries parameter indicates the chromaticitycoordinates of the source primaries. The transfer_characteristicsparameter indicates the opto-electronic transfer characteristic of thesource picture. The matrix_coeffs parameter describes the matrixcoefficients used in deriving luma and chroma signals from the green,blue, and red primaries.

According to another example, an SPS may be shared by layers withdifferent spatial resolutions, bit depth, or color formats in accordancewith the techniques of this disclosure. A video coder, such as videoencoder 20 or video decoder 30 may code the SPS. For example, videoencoder 20 may encode the SPS. The encoded SPS may be signalled,transmitted, or otherwise transferred by output interface 22 throughlink 16 or using storage device 34 and received by input interface 28.The encoded SPS may be decoded by video decoder 30.

According to another example, no timing information is provided in a VUIof SPSs with layer ID greater than 0 in accordance with the techniquesof this disclosure. A video coder, such as video encoder 20 or videodecoder 30 may code the SPS with a layer ID greater than 0, which doesnot include timing information in the VUI. For example, video encoder 20may encode the SPS. The encoded SPS may be signalled, transmitted, orotherwise transferred by output interface 22 through link 16 or usingstorage device 34 and received by input interface 28. The encoded SPSmay be decoded by video decoder 30.

According to another example, no explicit signaling of target outputlayers is provided for the default output layer sets in accordance withthe techniques of this disclosure. A video coder, such as video encoder20 or video decoder 30 may code the default output layer sets, whichdoes not include any explicit signaling of target output layers for thedefault output layer sets. For example, video encoder 20 encodes thedefault output layer sets. The encoded default output layer sets may besignalled, transmitted, or otherwise transferred by output interface 22through link 16 or using storage device 34 and received by inputinterface 28. The encoded default output layer sets may be decoded byvideo decoder 30.

According to another example, signaling of the maximum number oftemporal sub-layers that may be present (sps_max_sub_layers_minus1) andwhether inter prediction is additionally restricted(sps_temporal_id_nesting_flag) is absent in SPSs with layer ID(nuh_layer_id) greater than 0. A video coder, such as video encoder 20or video decoder 30 may code video data without coding, in SPSs withlayer ID greater than 0, the maximum number of temporal sub-layers thatmay be present in each CVS referring to the SPS and without codingwhether inter prediction is additionally restricted for CVSs referringto the SPS. For example, video encoder 20 may encode video data withoutcoding, in SPSs with layer ID greater than 0, the maximum number oftemporal sub-layers that may be present in each CVS referring to the SPSand whether inter prediction is additionally restricted for CVSsreferring to the SPS. The encoded information may be signalled,transmitted, or otherwise transferred by output interface 22 throughlink 16 or using storage device 34 and received by input interface 28.The encoded information may be decoded by video decoder 30.

According to another example, syntax element output_layer_set_idx[i] maybe changed to output_layer_set_idx_minus1[i] in accordance with thetechniques of this disclosure. A video coder, such as video encoder 20or video decoder 30 may code output_layer_set_idx_minus1[i] to indicatethe index of the layer set that corresponds to an output layer set.

FIG. 2 is a block diagram illustrating an example video encoder 20 thatmay implement the techniques described in this disclosure. Video encoder20 may perform intra- and inter-coding of video blocks within videoslices. Intra-coding relies on spatial prediction to reduce or removespatial redundancy in video within a given video frame or picture.Inter-coding relies on temporal prediction or inter-layer to reduce orremove temporal redundancy or inter-layer redundancy in video withinadjacent frames or pictures in the same layer or across different layersof a video sequence. Intra-mode (I mode) may refer to any of severalspatial based compression modes. Inter-modes, such as uni-directionalprediction (P mode) or bi-prediction (B mode), may refer to any ofseveral temporal-based compression modes.

In the example of FIG. 2, video encoder 20 includes video data memory40, a prediction processing unit 41, reference picture memory 64, summer50, transform processing unit 52, quantization processing unit 54, andentropy encoding processing unit 56. Prediction processing unit 41includes motion estimation processing unit 42, motion compensationprocessing unit 44, and intra prediction processing unit 46. For videoblock reconstruction, video encoder 20 also includes inversequantization processing unit 58, inverse transform processing unit 60,and summer 62. A deblocking filter (not shown in FIG. 2) may also beincluded to filter block boundaries to remove blockiness artifacts fromreconstructed video. If desired, the deblocking filter would typicallyfilter the output of summer 62. Additional loop filters (in loop or postloop) may also be used in addition to the deblocking filter.

Video data memory 40 may store video data to be encoded by thecomponents of video encoder 20. The video data stored in video datamemory 40 may be obtained, for example, from video source 18. A decodedpicture buffer (DPB) may be a reference picture memory 64 that storesreference video data for use in encoding video data by video encoder 20,e.g., in intra- or inter-coding modes. Video data memory 40 and the DPB(e.g., reference picture memory 64) may be formed by any of a variety ofmemory devices, such as dynamic random access memory (DRAM), includingsynchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM(RRAM), or other types of memory devices. Video data memory 40 and theDPB (e.g., reference picture memory 64) may be provided by the samememory device or separate memory devices. In various examples, videodata memory 101 may be on-chip with other components of video encoder20, or off-chip relative to those components.

As shown in FIG. 2, video encoder 20 receives video data, and predictionprocessing unit 41 partitions the data into video blocks. In some cases,prediction processing unit 41 may partition video data based on a ratedistortion analysis. Received video data may be formatted according toany of the sample formats described above. For example, video data maybe formatted according to the 4:2:2 sample format. Partitioning mayinclude partitioning video data into slices, tiles, or other largerunits, as well as video block partitioning, e.g., according to aquadtree structure of LCUs and CUs.

Video encoder 20 generally illustrates the components that encode videoblocks within a video slice to be encoded. The slice may be divided intomultiple video blocks (and possibly into sets of video blocks referredto as tiles). Prediction processing unit 41 may select one of aplurality of possible coding modes, such as one of a plurality of intracoding modes or one of a plurality of inter coding modes, for thecurrent video block based on error results (e.g., coding rate and thelevel of distortion). Prediction processing unit 41 may provide theresulting intra- or inter-coded block to summer 50 to generate residualblock data and to summer 62 to reconstruct the encoded block for use asa reference picture.

Intra prediction processing unit 46 within prediction processing unit 41may perform intra-predictive coding of the current video block relativeto one or more neighboring blocks in the same frame or slice as thecurrent block to be coded to provide spatial compression. Motionestimation processing unit 42 and motion compensation processing unit 44within prediction processing unit 41 perform inter-predictive coding ofthe current video block relative to one or more predictive blocks in oneor more reference pictures to provide temporal compression.

Motion estimation processing unit 42 may be configured to determine theinter-prediction mode for a video slice according to a predeterminedpattern for a video sequence. The predetermined pattern may designatevideo slices in the sequence as P slices or B slices. Motion estimationprocessing unit 42 and motion compensation processing unit 44 may behighly integrated, but are illustrated separately for conceptualpurposes. Motion estimation, performed by motion estimation processingunit 42, is the process of generating motion vectors, which estimatemotion for video blocks. A motion vector, for example, may indicate thedisplacement of a prediction unit (PU) of a video block within a currentvideo frame or picture relative to a predictive block within a referencepicture.

A predictive block, for inter-coding, may be a block that is found toclosely match the PU of the video block to be coded in terms of pixeldifference, which may be determined by sum of absolute difference (SAD),sum of square difference (SSD), or other difference metrics.Alternatively, a predictive block, for intra-coding, may be a block thatis formed based on spatial prediction with respect to pixel values fromone or more neighboring blocks. In some examples, for inter-prediction,video encoder 20 may calculate values for sub-integer pixel positions ofreference pictures stored in reference picture memory 64. For example,video encoder 20 may interpolate values of one-quarter pixel positions,one-eighth pixel positions, or other fractional pixel positions of thereference picture. Therefore, motion estimation processing unit 42 mayperform a motion search relative to the full pixel positions andfractional pixel positions and output a motion vector with fractionalpixel precision.

Motion estimation processing unit 42 calculates a motion vector for a PUof a video block in an inter-coded slice by comparing the position ofthe PU to the position of a predictive block of a reference picture. Thereference picture may be selected from a first reference picture list(List 0) or a second reference picture list (List 1), each of whichidentify one or more reference pictures stored in reference picturememory 64. Motion estimation processing unit 42 sends the calculatedmotion vector to entropy encoding processing unit 56 and motioncompensation processing unit 44.

Motion compensation, performed by motion compensation processing unit44, may involve fetching or generating the predictive block based on themotion vector determined by motion estimation, possibly performinginterpolations to sub-pixel precision. Upon receiving the motion vectorfor the PU of the current video block, motion compensation processingunit 44 may locate the predictive block to which the motion vectorpoints in one of the reference picture lists.

Video encoder 20 forms a residual video block, for inter or intracoding, by subtracting pixel values of the predictive block from thepixel values of the current video block being coded, forming pixeldifference values. The pixel difference values form residual data forthe block, and may include both luma and chroma difference components.Summer 50 represents the component or components that perform thissubtraction operation. Motion compensation processing unit 44 may alsogenerate syntax elements associated with the video blocks and the videoslice for use by video decoder 30 in decoding the video blocks of thevideo slice.

Intra-prediction processing unit 46 may intra-predict a current block,as an alternative to the inter-prediction performed by motion estimationprocessing unit 42 and motion compensation processing unit 44, asdescribed above. In particular, intra-prediction processing unit 46 maydetermine an intra-prediction mode to use to encode a current block. Insome examples, intra-prediction processing unit 46 may encode a currentblock using various intra-prediction modes, e.g., during separateencoding passes, and intra-prediction processing unit 46 (or a modeselect processing unit, in some examples) may select an appropriateintra-prediction mode to use from the tested modes.

For example, intra-prediction processing unit 46 may calculaterate-distortion values using a rate-distortion analysis for the varioustested intra-prediction modes, and select the intra-prediction modehaving the best rate-distortion characteristics among the tested modes.Rate-distortion analysis generally determines an amount of distortion(or error) between an encoded block and an original, unencoded blockthat was encoded to produce the encoded block, as well as a bit rate(that is, a number of bits) used to produce the encoded block.Intra-prediction processing unit 46 may calculate ratios from thedistortions and rates for the various encoded blocks to determine whichintra-prediction mode exhibits the best rate-distortion value for theblock. It should be noted that rate-distortion analysis may be performedon an combination of the color components.

In any case, after selecting an intra-prediction mode for a block,intra-prediction processing unit 46 may provide information indicativeof the selected intra-prediction mode for the block to entropy encodingprocessing unit 56. Entropy encoding processing unit 56 may encode theinformation indicating the selected intra-prediction mode in accordancewith the techniques of this disclosure. Video encoder 20 may include inthe transmitted bitstream configuration data, which may include aplurality of intra-prediction mode index tables and a plurality ofmodified intra-prediction mode index tables (also referred to ascodeword mapping tables), definitions of encoding contexts for variousblocks, and indications of a most probable intra-prediction mode, anintra-prediction mode index table, and a modified intra-prediction modeindex table to use for each of the contexts. The bitstream may also (oralternatively) be stored onto storage device 34 for later access bydestination device 14 or other devices, for decoding and/or playback.

After prediction processing unit 41 generates the predictive block forthe current video block via either inter prediction or intra prediction,video encoder 20 forms a residual video block by subtracting thepredictive block from the current video block. The residual video datain the residual block may be included in one or more transform units(TUs) and applied to transform processing unit 52. Note that transformprocessing unit 52 refers to a component, module, processor orprocessors, or functional unit of video encoder 20, and should not beconfused with a TU, which is a basic unit of data for the transform andquantization process. Transform processing unit 52 transforms theresidual video data into residual transform coefficients using atransform, such as a discrete cosine transform (DCT) or a conceptuallysimilar transform. Transform processing unit 52 may convert the residualvideo data from a pixel domain to a transform domain, such as afrequency domain. Transform processing unit 52 may send the resultingtransform coefficients to quantization processing unit 54.

In the illustrated example of FIG. 2, a video encoder 20 may refer toone of the profile, tier, and level syntax structures for each of aplurality of output layer sets and encode video data of one of theoutput layer sets based on information from the profile, tier, and levelsyntax structure referred to for the output layer set.

Video encoder 20 may transmit a non-entropy encoded set of profile,tier, and level syntax structures. The non-entropy encoded set ofprofile, tier, and level syntax structures may be at a position within aVPS extension prior to syntax elements of the VPS extension that areentropy encoded, such that an intermedia networking device, splicingengine, media aware network element, or decoder can parse thenon-entropy encoded set of profile, tier, and level syntax structureswithout the need for entropy coding.

In some examples, the video encoder 20 may transmit or receive an SPSwith a nuh_layer_id equal to 0, wherein the SPS includes a profile,tier, and level syntax structure for a layer of video data. For example,video encoder 20 may send an SPS with a nuh_layer_id equal to 0, whereinthe SPS includes a profile, tier, and level syntax structure for a layerof video data.

Video encoder 20 may encode the output layer set based on the outputlayer flag [i][j]. Video encoder 20 may also transmit an output layerflag [i] [j] that, when equal to 1, specifies that a j-th layer in thelayer set is a target output layer of an i-th output layer set, and,when equal to 0, specifies that the j-th layer in the layer set is notthe target output layer of the i-th output layer set.

Video encoder 20 may non-entropy encode some video data of one or moreof the layers of video data. The non-entropy encoded video data mayinclude layer dependency information. The layer dependency informationmay indicate whether one of the layers is a direct reference layer foranother of the layers. In some examples, the layer dependencyinformation includes a direct_dependency_flag[i][j] that, when equal to0, specifies that a layer with index j is not a direct reference layerfor a layer with index I, and when equal to 1, specifies that the layerwith index j may be a direct reference layer for the layer with index i.

Video encoder 20 may transmit the non-entropy encoded layer dependencyinformation at a position within a VPS extension prior to syntaxelements of the VPS extension that are entropy encoded.

According to one example, video encoder 20 may encode more than oneoutput layer set for one layer set. In some examples, the encoding maybe performed by entropy encoding processing unit 56.

According to another example, video encoder 20 may encode all profile,tier, level information in the VPS, potentially in a way that it isaccessible without entropy decoding, i.e., without entropy encoding theprofile, tier, and/or level information. In some examples, the encodingmay be performed by entropy encoding processing unit 56, however,without entropy encoding. Accordingly, entropy encoding processing unitmay perform other types of encoding in addition to entropy encoding.

According to another example, video encoder 20 may encode layerdependency information in the VPS such that it is accessible withoutentropy decoding, i.e., without entropy encoding the layer dependencyinformation. In some examples, the encoding may be performed by entropyencoding processing unit 56, however, without entropy encoding.Accordingly, entropy encoding processing unit may perform other types ofencoding in addition to entropy encoding.

According to another example, video encoder 20 may encode representationformat in the VPS, potentially in a way that it is accessible withoutentropy decoding, i.e., without entropy encoding the representationformat in the VPS. In some examples, each layer may be associated with aparticular representation format. In some examples, the encoding may beperformed by entropy encoding processing unit 56, however, withoutentropy encoding. Accordingly, entropy encoding processing unit mayperform other types of encoding in addition to entropy encoding. Videoencoder 20 or may encode representation format in the VPS, potentiallyin a way that it is accessible without entropy decoding in accordancewith the techniques of this disclosure, and each layer may be associatedwith a particular representation format.

According to another example, video encoder 20 may code visual signalinformation (video_format, video_full_range_flag, colour_primaries,transfer_characteristics, matrix_coeffs) per layer in the VPS inaccordance with the techniques of this disclosure. In some examples, theencoding may be performed by entropy encoding processing unit 56.

According to another example, an SPS may be shared by layers withdifferent spatial resolutions, bit depth, or color formats in accordancewith the techniques of this disclosure. Video encoder 20 may encode theSPS. In some examples, the encoding may be performed by entropy encodingprocessing unit 56.

According to another example, no timing information is provided in VUIof SPS with layer ID greater than 0 in accordance with the techniques ofthis disclosure. Video encoder 20 may encode the SPS. In some examples,the encoding may be performed by entropy encoding processing unit 56.

According to another example, no explicit signaling of target outputlayers is provided for the default output layer sets in accordance withthe techniques of this disclosure. Video encoder 20 may encode thedefault output layer sets. In some examples, the encoding may beperformed by entropy encoding processing unit 56.

According to another example, signaling of the maximum number oftemporal sub-layers that may be present (sps_max_sub_layers_minus1) andwhether inter prediction is additionally restricted(sps_temporal_id_nesting_flag) occurs in an SPS only when thenuh_layer_id is equal to 0, i.e. not signalled in SPS with layer IDgreater than 0. Video encoder 20 may encode video data without coding inSPSs with layer ID greater than 0 the maximum number of temporalsub-layers that may be present in each CVS referring to the SPS andwhether inter prediction is additionally restricted for CVSs referringto the SPS. In some examples, the encoding may be performed by entropyencoding processing unit 56.

According to another example, syntax element output_layer_set_idx[i] maybe changed to output_layer_set_idx_minus1[i] in accordance with thetechniques of this disclosure. Video encoder 20 may encode the syntaxelement output_layer_set_idx_minus1[i] to indicate the index of thelayer set that corresponds to the i-th output layer set specified by theVPS. In some examples, the encoding may be performed by entropy encodingprocessing unit 56.

FIG. 3 is a block diagram illustrating an example video decoder 30 thatmay implement the techniques described in this disclosure. In theexample of FIG. 3, video decoder 30 includes video data memory 78, anentropy decoding processing unit 80, prediction processing unit 81,inverse quantization processing unit 86, inverse transformationprocessing unit 88, summer 90, and reference picture memory 92.Prediction processing unit 81 includes motion compensation processingunit 82 and intra prediction processing unit 84. Video decoder 30 may,in some examples, perform a decoding pass generally reciprocal to theencoding pass described with respect to video encoder 20 from FIG. 2.

Video data memory 78 may store video data, such as an encoded videobitstream, to be decoded by the components of video decoder 30. Thevideo data stored in video data memory 78 may be obtained, for example,from a computer-readable medium, e.g., from a local video source, suchas a camera, via wired or wireless network communication of video data,or by accessing physical data storage media. Video data memory 78 mayform a coded picture buffer (CPB) that stores encoded video data from anencoded video bitstream. A decoded picture buffer (DPB) may be areference picture memory 92 that stores reference video data for use indecoding video data by video decoder 30, e.g., in intra- or inter-codingmodes. Video data memory 78 and the DPB may be formed by any of avariety of memory devices, such as dynamic random access memory (DRAM),including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM),resistive RAM (RRAM), or other types of memory devices. Video datamemory 78 and the DPB may be provided by the same memory device orseparate memory devices. In various examples, video data memory 78 maybe on-chip with other components of video decoder 30, or off-chiprelative to those components.

During the decoding process, video decoder 30 receives an encoded videobitstream that represents video blocks of an encoded video slice andassociated syntax elements from video encoder 20. Entropy decodingprocessing unit 80 of video decoder 30 entropy decodes the bitstream togenerate quantized coefficients, motion vectors, and other syntaxelements. Entropy decoding processing unit 80 forwards the motionvectors and other syntax elements to prediction processing unit 81.Video decoder 30 may receive the syntax elements at the video slicelevel and/or the video block level.

When the video slice is coded as an intra-coded (I) slice, intraprediction processing unit 84 of prediction processing unit 81 maygenerate prediction data for a video block of the current video slicebased on a signalled intra prediction mode and data from previouslydecoded blocks of the current frame or picture. When the video frame iscoded as an inter-coded (i.e., B or P) slice, motion compensationprocessing unit 82 of prediction processing unit 81 produces predictiveblocks for a video block of the current video slice based on the motionvectors and other syntax elements received from entropy decodingprocessing unit 80. The predictive blocks may be produced from one ofthe reference pictures within one of the reference picture lists. Videodecoder 30 may construct the reference frame lists, List 0 and List 1,using default construction techniques based on reference pictures storedin reference picture memory 92.

Motion compensation processing unit 82 determines prediction informationfor a video block of the current video slice by parsing the motionvectors and other syntax elements, and uses the prediction informationto produce the predictive blocks for the current video block beingdecoded. For example, motion compensation processing unit 82 uses someof the received syntax elements to determine a prediction mode (e.g.,one of a plurality of inter-prediction modes) used to code the videoblocks of the video slice, an inter-prediction slice type (e.g., B sliceor P slice), construction information for one or more of the referencepicture lists for the slice, motion vectors for each inter-encoded videoblock of the slice, inter-prediction status for each inter-coded videoblock of the slice, and other information to decode the video blocks inthe current video slice.

Motion compensation processing unit 82 may also perform interpolationbased on interpolation filters. Motion compensation processing unit 82may use interpolation filters as used by video encoder 20 duringencoding of the video blocks to calculate interpolated values forsub-integer pixels of reference blocks. In this case, motioncompensation processing unit 82 may determine the interpolation filtersused by video encoder 20 from the received syntax elements and use theinterpolation filters to produce predictive blocks.

Inverse quantization processing unit 86 inverse quantizes, i.e.,de-quantizes, the quantized transform coefficients provided in thebitstream and decoded by entropy decoding processing unit 80. Theinverse quantization process may include use of a quantization parametercalculated by video encoder 20 for each video block in the video sliceto determine a degree of quantization and, likewise, a degree of inversequantization that should be applied.

Inverse transform processing unit 88 receives transform coefficients andapplies an inverse transform, e.g., an inverse DCT, an inverse integertransform, or a conceptually similar inverse transform process, to thetransform coefficients in order to produce residual blocks in the pixeldomain. In some examples, inverse transform processing unit 88 mayreceive transform coefficients that were generated by a video encoderbased on the transform unit partitioning techniques.

After motion compensation processing unit 82 or intra predictionprocessing unit 84 generates the predictive block for the current videoblock based on the motion vectors and other syntax elements, videodecoder 30 forms a decoded video block by summing the residual blocksfrom inverse transform processing unit 88 with the correspondingpredictive blocks generated by motion compensation processing unit 82.Summer 90 represents the component or components that perform thissummation operation.

If desired, a deblocking filter may also be applied to filter thedecoded blocks in order to remove blockiness artifacts. Other loopfilters (either in the coding loop or after the coding loop) may also beused to smooth pixel transitions, or otherwise improve the videoquality. The decoded video blocks in a given frame or picture are thenstored in reference picture memory 92, which stores reference picturesused for subsequent motion compensation. Reference picture memory 92also stores decoded video for later presentation on a display device,such as display device 32 of FIG. 1.

In the illustrated example of FIG. 3 video decoder 30 may receive anon-entropy encoded set of profile, tier, and level syntax structures.

Video decoder 30 may refer to one of the profile, tier, and level syntaxstructures for each of a plurality of output layer sets and decode videodata of one of the output layer sets based on information from theprofile, tier, and level syntax structure referred to for the outputlayer set.

In some examples, the video coder may transmit or receive an SPS with anuh_layer_id equal to 0, wherein the SPS includes a profile, tier, andlevel syntax structure for a layer of video data. Video decoder 30 mayreceive an SPS with a nuh_layer_id equal to 0, wherein the SPS includesa profile, tier, and level syntax structure for a layer of video data.

In some examples, when a layer with nuh_layer_id greater than 0 refersto the SPS, video decoder 30 might not decode video data of the layerwith nuh_layer_id greater than 0 using the profile, tier, and levelsyntax structure of the SPS.

Video decoder 30 may transmit an output layer flag [i] [j] that, whenequal to 1, specifies that a j-th layer in the layer set is a targetoutput layer of an i-th output layer set, and, when equal to 0,specifies that the j-th layer in the layer set is not the target outputlayer of the i-th output layer set.

Video decoder 30 may also generate the output layer set based on theoutput layer flag [i] [j].

In the illustrated example of FIG. 3, video decoder 30 may decodemultilayer video data including layers of video data.

Video decoder 30 may receive a non-entropy encoded layer dependencyinformation at a position within a VPS extension prior to syntaxelements of the VPS extension that are entropy encoded.

Video decoder 30 may encode video data of one or more of the layers ofvideo data based on the non-entropy encoded layer dependencyinformation. The layer dependency information indicates whether one ofthe layers may be a direct reference layer for another of the layers.

In some examples, the layer dependency information includes adirect_dependency_flag[i][j] that, when equal to 0, specifies that alayer with index j is not a direct reference layer for a layer withindex i, and when equal to 1, specifies that the layer with index j maybe a direct reference layer for the layer with index i.

In some examples, this disclosure describes methods for enhanced designsof VPS and SPS for HEVC extensions, including changes to signaling ofprofile, tier, and level information for output layer sets, signaling ofoutput layer sets, and signaling of layer dependency. In some examples,this disclosure also describes methods for enhanced designs of VPS andSPS for HEVC extensions, including changes to signaling of informationon representation format (spatial resolution, color format, and bitdepth in the VPS (extension) for session negotiation as well asefficient signaling of SPS parameters with individual control ofdifferent categories.

In some examples, the current VPS and SPS designs may be associated atleast with the following problems: (1) because the syntax elementvps_num_layer_sets_minus1 is ue(v) coded and there are also other ue(v)coded syntax elements before it, currently accessing of the profile,tier, and level for layer sets needs entropy decoding; (2) similarly,layer dependency information is not accessible without entropy decoding;and (3) signaling of output layer set is problematic and not efficient,because: (a) the syntax element layer_id_included_flag[ ][ ] used foroutput_layer_set_idx[i] equal to 0 is for layer set 0, while for layerset 0 layer_id_included_flag[ ][ ] is not defined in HEVC version 1(i.e. HEVC WD10), (b) it is clear that the target output layer for layerset 0 is layer 0 (the base layer) anyway, (c) currently at most oneoutput layer set can be signalled for each layer set and (d) currently,the syntax uses a loop of layer IDs from 0 to the greatest possiblelayer ID in the VPS is complicated.

In multiview scenarios, the case is often that one layer set isassociated with multiple sets of different target output layers. Thus,the syntax element output_layer_flag[lsIdx][j] is changed tooutput_layer_flag[i][j], and related semantics are changed accordingly,and, as mentioned above in item (d), currently, the syntax uses a loopof layer IDs from 0 to the greatest possible layer ID in the VPS iscomplicated. It would be much simpler just to use a loop of the layersin the layer set, excluding the highest layer in the layer set as thatlayer is surely a target output layer.

According to one example, video decoder 30 may decode more than oneoutput layer set for one layer set. In some examples, the decoding maybe performed by entropy encoding processing unit 80.

According to another example, video decoder 30 may decode all profile,tier, level information in the VPS, potentially in a way that it isaccessible without having to entropy decoding. In some examples, thedecoding may be performed by entropy decoding processing unit 80,however, without entropy decoding. Accordingly, decoding may also beperformed by devices that do not have an entropy decoder.

According to another example, video decoder 30 may decode layerdependency information in the VPS such that it is accessible withoutentropy decoding. In some examples, the decoding may be performed byentropy decoding processing unit 80, however, without entropy encoding.Accordingly, decoding may also be performed by devices that do not havean entropy decoder.

According to another example, video decoder 30 may decode representationformat in the VPS, potentially in a way that it is accessible withoutentropy decoding, i.e., without entropy encoding the representationformat in the VPS. In some examples, the decoding may be performed byentropy decoding processing unit 80, however, without entropy decoding.Accordingly, decoding may also be performed by devices that do not havean entropy decoder. Video decoder 30 may decode representation format inthe VPS, potentially without entropy decoding in accordance with thetechniques of this disclosure, and each layer may be associated with aparticular representation format.

According to another example, video decoder 30 may decode visual signalinformation (video_format, video_full_range_flag, colour_primaries,transfer_characteristics, matrix_coeffs) per layer in the VPS inaccordance with the techniques of this disclosure. In some examples, theencoding may be performed by entropy encoding processing unit 80. Insome examples, the video_format parameter indicates a format of arepresentation of pictures to be coded. The video_full_range_flagparameter indicates the black level and range of the luma and chromasignals. The colour_primaries parameter indicates the chromaticitycoordinates of the source primaries. The transfer_characteristicsparameter indicates the opto-electronic transfer characteristic of thesource picture. The matrix_coeffs parameter describes the matrixcoefficients used in deriving luma and chroma signals from the green,blue, and red primaries.

According to another example, an SPS may be shared by layers withdifferent spatial resolutions, bit depth, or color formats in accordancewith the techniques of this disclosure. Video decoder 30 may decode theSPS. In some examples, the encoding may be performed by entropy encodingprocessing unit 80.

According to another example, no timing information is provided in VUIof SPSs with layer ID greater than 0 in accordance with the techniquesof this disclosure. Video decoder 30 may decode the SPS. In someexamples, the decoding may be performed by entropy decoding processingunit 80.

According to another example, no explicit signaling of target outputlayers is provided for the default output layer sets in accordance withthe techniques of this disclosure. Video decoder 30 may decode thedefault output layer sets. In some examples, the decoding may beperformed by entropy decoding processing unit 80.

According to another example, signaling of the maximum number oftemporal sub-layers that may be present (sps_max_sub_layers_minus1) andwhether inter prediction is additionally restricted(sps_temporal_id_nesting_flag) occurs in an SPS only when nuh_layer_idis equal to 0. Video decoder 30 may decode video data without coding, inSPSs with layer ID greater than 0, the maximum number of temporalsub-layers that may be present in each CVS referring to the SPS andwhether inter prediction is additionally restricted for CVSs referringto the SPS. In some examples, the decoding may be performed by entropydecoding processing unit 80.

According to another example, syntax element output_layer_set_idx[i] maybe changed to output_layer_set_idx_minus1[i] in accordance with thetechniques of this disclosure. Video decoder 30 may decode the syntaxelement output_layer_set_idx_minus1[i] to indicate the index of thelayer set corresponding to the i-th output layer set specified by theVPS.

In the examples below, bracketed labels (e.g., [START EXAMPLE A] and[END EXAMPLE A]) will be used to indicate text related to the exampleindicated. Changes may be indicated with respect to a current version ofthe SHVC, which as of Apr. 2, 2013 is downloadable from:http://phenix.int-evry.fr/jct/doc_end_user/documents/12_Geneva/wg11/JCTVC-L1008-v1.zipor MV-HEVC standard, which as of Apr. 2, 2013 is downloadable from:http://phenix.it-sudparis.eu/jct2/doc_end_user/documents/3_Geneva/wg11/JCT3V-C1004-v4.zip

Several changes on signaling of profile, tier, and level information forlayer sets, signaling of output layer sets, and signaling of layerdependency, are indicated by [START EXAMPLE A] and [END EXAMPLE A] whichwill be used in this submission to indicate example A included herein,according to aspects of this disclosure.

Due to the fact that the syntax element vps_num_layer_sets_minus1 isue(v) coded (i.e., entropy encoded) and there are also other ue(v) codedsyntax elements before it, currently accessing of the profile, tier, andlevel for layer sets needs entropy decoding. For this information to beaccessible without entropy decoding, a set of profile_tier_level( )syntax structures may be signalled at a position that is accessiblewithout entropy decoding. The set of profile_tier_level( ) syntaxstructures may then be referenced for linking to output layer sets.Multiple output layer sets of the same layer set may need different DPBsizes, and hence can conform to different levels.

In some examples, the syntax element output_layer_set_idx[i] may bechanged to output_layer_set_idx_minus1[i], as described below. When anSPS with nuh_layer_id equal to 0 is referred by a layer withnuh_layer_id greater than 0, the profile_tier_level( ) syntax structurein the SPS is not applied for that layer. For the similar reason asabove, the signaling of layer dependency is moved up to be accessiblewithout entropy decoding. Changing of the syntax elementoutput_layer_set_idx[i] to output_layer_set_idx_minus1[i] is due to thefollowing reasons. The syntax element layer_id_included_flag[ ][ ] usedfor output_layer_set_idx[i] equal to 0 is for layer set 0, while forlayer set 0 layer_id_included_flag[ ][ ] is not defined. It is clearthat the target output layer for layer set 0 is layer 0 (the baselayer).

Accordingly, as can be seen above, each layer needs to refer to an SPS.Conventionally, any two layers that are of different values of spatialresolutions, bit depths, or color formats have to refer to two differentSPSs as these representation format parameters are signalled in the SPS.However, when these parameters for all SPSs except those withnuh_layer_id equal to 0 are moved to the VPS, and when it is specifiedthat the representation format parameters in an SPS with nuh_layer_idequal to 0 that is referred to by a layer with nuh_layer_id greater than0 are ignored, it is possible for layers with different values ofspatial resolutions, bit depths, or color formats to refer to the sameSPSs. In other words, according to some embodiments of this disclosure,layers with different values of spatial resolutions, bit depths, orcolor formats can share the same SPSs, as long as other SPS.

Some examples described herein may change the syntax and semantics foroutput layer set signaling. In some cases, this may solve one or more ofthe following issues, first currently at most one output layer set canbe signalled for each layer set. In multiview scenarios, the case isoften that one layer set is associated with multiple sets of differenttarget output layers. Thus, the syntax elementoutput_layer_flag[lsIdx][j] may be changed to output_layer_flag[i][j],and related semantics are changed accordingly. Accordingly, more thanone output layer set may be signalled for one layer set. Second,currently, the syntax uses a loop of layer IDs from 0 to the greatestpossible layer ID in the VPS, which is complicated. Rather, it would bemuch simpler just to use of a loop of the layers in the layer set,excluding the highest layer in the layer set as that layer is surely atarget output layer.

Signaling of information on representation format (spatial resolution,colour format, and bit depth in the VPS (extension) for sessionnegotiation, for which the changes are indicated using bracketed labels[START EXAMPLE B] and [END EXAMPLE B] which will be used in thissubmission to indicate example B. The representation format is signalledfor each layer, including the base layer, through an index to a list ofsuch information, and is not signalled in SPSs with nuh_layer_id greaterthan 0, same as for the profile_tier_level( ) syntax structure.Consequently, this also reduces redundantly sending the samerepresentation format information in different SPSs with nuh_layer_idgreater than 0. When an SPS with nuh_layer_id equal to 0 is referred bya layer with nuh_layer_id greater than 0, the values of the syntaxelements chroma_format_idc, separate_colour_plane_flag,pic_width_in_luma_samples, pic_height_in_luma_samples,bit_depth_luma_minus8, and bit_depth_chroma_minus8 are not applied forthat layer.

When efficient signaling of SPS parameters with individual control ofdifferent categories, the parameters that may be included in SPSs may beclassified into the following six categories: (1) Cat1:profile-tier-level information, already addressed in Scalable HEVC VideoCoding (SHVC) WD1 and Multi-View HEVC (MV-HEVC) WD3 and above, (2) Cat2:representation format information, addressed above, (3) Cat3: sub-layerinformation (sps_max_sub_layers_minus1, sps_temporal_id_nesting_flag,sps_max_dec_pic_buffering_minus1 [i], sps_max_num_reorder_pics[i], andsps_max_latency_increase_plus1[i]) (These changes are indicated bybracketed labels [START EXAMPLE C] and [END EXAMPLE C] which will beused in this submission to indicate example C, which is also referred toas and Cat3), (4) Cat4: short-term reference picture set (RPS)candidates (the changes for this are indicated by bracketed labels[START EXAMPLE D] and [END EXAMPLE D], which will be used in thissubmission to indicate example D, which is also referred to as Cat4, (5)Cat5: Video Usability Information (VUI) parameters (the changes for thisare indicated by bracketed labels [START EXAMPLE E] and [END EXAMPLE E],which will be used in this submission to indicate example E, which isalso referred to as Cat 5), and (6) Cat6: other SPS parameters, thechanges for this and the common changes are indicated by bracketedlabels [START EXAMPLE F] and [END EXAMPLE F] will be used in thissubmission to indicate example F, also referred to as Cat6.

For enhancement layers or layer sets involving enhancement layers,information of categories 3 to 6 may be either inherited from the activeVPS or directly signalled in the SPS, while information of categories 1and 2 has to be signalled in the VPS due to the importance for sessionnegotiation. In an SPS with nuh_layer_id greater than 0, to the minimumonly three syntax elements to signal the VPS ID, SPS ID and a flag (toindicate whether data of categories 3 to 6 (Cat3 to Cat6) are present inthe SPS or inherited from the active VPS) are present. Such a dummySPS's role is only to pass the active VPS ID to the Picture ParameterSets (PPS) and then indirectly to the Video Coding Layer (VCL) NetworkAbstraction Layer (NAL) units.

Changes below are based on MV-HEVC WD3 and SHVC WD1 and are identified,as noted above, and removals are shown within brackets after the word“removed:,” e.g., [removed: . . . ].” Parts that are not mentioned arethe same as in MV-HEVC WD3 and SHVC WD1.

Illustrated below in Table 3 is example syntax for a video parameter set(VPS) for the raw byte sequence payload (RBSP) syntax and semantics.This is the same as in SHVC WD1 and MV-HEVC WD3. The syntax is copiedbelow (in Table 3) for convenience.

TABLE 3 Example syntax for VPS for RBSP syntax and semanticsvideo_parameter_set_rbsp( ) { Descriptor vps_video_parameter_set_id u(4)vps_reserved_three_2bits u(2) vps_max_layers_minus1 u(6)vps_max_sub_layers_minus1 u(3) vps_temporal_id_nesting_flag u(1)vps_extension_offset //vps_reserved_0xffff_16bits u(16)profile_tier_level( 1, vps_max_sub_layers_minus1 )vps_sub_layer_ordering_info_present_flag u(1) for( i = (vps_sub_layer_ordering_info_present_flag ? 0 : vps_max_sub_layers_minus1);       i <= vps_max_sub_layers_minus1; i++ ) {  vps_max_dec_pic_buffering_minus1[ i ] ue(v)  vps_max_num_reorder_pics[ i ] ue(v)   vps_max_latency_increase_plus1[i ] ue(v) } vps_max_layer_id u(6) vps_num_layer_sets_minus1 ue(v) for( i= 1; i <= vps_num_layer_sets_minus1; i++ )   for( j = 0; j <=vps_max_layer_id; j++ )     layer_id_included_flag[ i ][ j ] u(1)vps_timing_info_present_flag u(1) if( vps_timing_info_present_flag ) {  vps_num_units_in_tick u(32)   vps_time_scale u(32)  vps_poc_proportional_to_timing_flag u(1)   if(vps_poc_proportional_to_timing_flag )    vps_num_ticks_poc_diff_one_minus1 ue(v)   vps_num_hrd_parametersue(v)   for( i = 0; i < vps_num_hrd_parameters; i++ ) {    hrd_layer_set_idx[ i ] ue(v)     if( i > 0 )      cprms_present_flag[ i ] u(1)     hrd_parameters(cprms_present_flag[ i ], vps_max_sub_layers_minus1 )   } }vps_extension_flag u(1) if( vps_extension_flag ) {   vps_extension( )  vps_extension2_flag u(1)   if( vps_extension2_flag )     while(more_rbsp_data( ) )       vps_extension_data_flag u(1) }rbsp_trailing_bits( ) }

Table 4 illustrates an example of video parameter set extension andsemantics.

TABLE 4 Video parameter set extension syntax and semanticsvps_extension( ) { Descriptor while( !byte_aligned( ) )  vps_extension_byte_alignment_reserved_one_bit u(1) avc_base_layer_flagu(1) splitting_flag u(1) for( i = 0, NumScalabilityTypes = 0; i < 16;i++ ) {   scalability_mask[ i ] u(1)   NumScalabilityTypes +=scalability_mask[ i ] } for( j = 0; j <NumScalabilityTypes; j++ )  dimension_id_len_minus1[ j ] u(3) vps_nuh_layer_id_present_flag u(1)for( i = 1; i <= vps_max_layers_minus1; i++ ) {   if(vps_nuh_layer_id_present_flag )     layer_id_in_nuh[ i ] u(6)   for( j =0; j < NumScalabilityTypes; j++ )     dimension_id[ i ][ j ] u(v) }[START EXAMPLE A]  vps_num_profile_tier_level_minus1 u(6) for( i = 1; i<= vps_num_profile_tier_level_minus1; i++ ) {  vps_profile_present_flag[ i ] u(1)   if( !vps_profile_present_flag[ i] )     profile_ref_minus1[ i ] u(6)   profile_tier_level(vps_profile_present_flag[ i ], vps_max_sub_layers_minus1 ) } for( i = 1;i <= vps_max_layers_minus1; i++ )   for( j = 0; j < i; j++ )    direct_dependency_flag[ i ][ j ] u(1) [END EXAMPLE A] [START EXAMPLEB]  vps_num_rep_fromats u(4) for( i = 0; i < vps_num_rep_fromats; i++ )  rep_format( ) for( i = 1; i <= vps_max_layers_minus1; i++ )   if(vps_num_rep_fromats > 1)     vps_rep_format_idx[ i ] u(4) [END EXAMPLEB] [START EXAMPLE C]  for( i = 1; i <= vps_max_layers_minus1; i++ ) {  max_sub_layers_vps_predict_flag[ i ] u(1)   if(!max_sub_layers_vps_predict_flag[ i ] )     max_sub_layers_vps_minus1[ i] u(3) } // fixed-length-coded info until above [END EXAMPLE C] [STARTEXAMPLE A]  multiple_output_layer_sets_in_layer_set_flag u(1) if(!multiple_output_layer_sets_in_layer_set_flag )   numOutputLayerSets =vps_num_layer_sets_minus1 + 1 else {   num_output_layer_sets_minus1ue(v)   numOutputLayerSets = num_output_layer_sets_minus1 + 1 } for( i =1; i < numOutputLayerSets; i++ ) {   if( i > vps_num_layer_sets_minus1 ){     output_layer_set_idx_minus1[ i ] u(v)     lsIdx =output_layer_set_idx_minus1[ i ] + 1     for( j = 0 ; j <NumLayersInIdList[ lsIdx ] − 1; j++)       output_layer_flag[ i ][ j ]u(1)   }   profile_level_tier_idx[ i ] u(v) } [removed: for( lsIdx = 1;lsIdx <= vps_num_layer_sets_minus1; lsIdx ++ ) {] [removed:  vps_profile_present_flag[ lsIdx ] [removed: u(1)] [removed:   if(!vps_profile_present_flag[ lsIdx ] )] [removed:    profile_layer_set_ref_minus1[ lsIdx ]] [removed: ue(v)] [removed:    profile_tier_level( vps_profile_present_flag[ lsIdx ],vps_max_sub_layers_minus1)]  [removed:}]  [removed:  num_output_layer_sets] [removed: ue(v)]   [removed:   for( i = 0; i <num_output_layer_sets; i++ ) {]   [removed:     output_layer_set_idx[ i]] [removed: ue(v)] [removed:   lsIdx = output_layer_set_idx[ i ]] [removed:     for( j = 0 ; j <= vps_max_layer_id; j++)]  [removed:    if( layer_id_included_flag[ lsIdx ][ j ] )]   [removed:        output_layer_flag[ lsIdx ][ j ]] [removed: u(1)] [removed:}][removed:for( i = 1; i <= vps_max_layers_minus1; i++ )]  [removed:  for(j = 0; j < i; j++ )]  [removed:     direct_dependency_flag[ i ][ j ]][removed: u(1)] [END EXAMPLE A] [START EXAMPLEF]  vps_num_other_sps_params ue(v) for( i = 0; i <vps_num_other_sps_params; i++)   other_sps_parameters( ) [END EXAMPLE F][START EXAMPLE D]  vps_num_st_rps_candidates ue(v) for( i = 0; i <vps_num_st_rps_candidates; i++ )   short_term_rps_candidates( ( i = = 0) ? 0 : 1 )[END EXAMPLE D] [START EXAMPLE E]  vps_num_vui_params ue(v)for( i = 0; i < vps_num_vui_params; i++ )   vui_parameters( 0 ) [ENDEXAMPLE E] [START EXAMPLE F]  for( i = 1; i <= vps_max_layers_minus1;i++ ) {   if( vps_num_other_sps_params > 1 )    vps_other_sps_params_idx[ i ] u(v) [END EXAMPLE F] [START EXAMPLED]  if( vps_num_st_rps_candidates > 1 )     vps_st_rps_idx[ i ] u(v)[END EXAMPLE D] [START EXAMPLE E]  if( vps_num_vui_params > 1 )    vps_vui_params_idx[ i ] u(v) } [END EXAMPLE E] [START EXAMPLEC]    for( i = 1; i < numOutputLayerSets; i++ ) {  sub_layer_vps_buf_info_predict_flag[ i ] u(1)   if(!sub_layer_vps_buff_info_predict_flag[ i ] ) {    sub_layer_vps_buf_info_present_flag[ i ] u(1)     for( j =(sub_layer_vps_buf_info_present_flag[ i ] ? 0 : MaxSubLayers[ i ] − 1 );              j <= MaxSubLayers[ i ] − 1; j++   )      max_vps_dec_pic_buffering_minus1[ i ][ j ] ue(v)   } } for( i = 1;i <= vps_max_layers_minus1; i++ ) {   if(max_sub_layers_vps_predict_flag[ i ] )    sub_layer_vps_ordering_info_predict_flag[ i ] u(1)   if(!sub_layer_ordering_info_predict_flag[ i ] ) {    sub_layer_vps_ordering_info_present_flag[ i ] u(1)     for( j = (sub_layer_vps_ordering_info_present_flag[ i ] ? 0 :            max_sub_layers_vps_minus1[ i ] ); j <=max_sub_layers_vps_minus1[ i ]; j++ )       max_vps_num_reorder_pics[ i][ j ] ue(v)       max_vps_latency_increase_plus1[ i ][ j ] ue(v)     }  } } [END EXAMPLE C] }

[START EXAMPLE A]

The parameter vps_num_profile_tier_level_minus1 plus 1 specifies thenumber of profile_tier_level( ) syntax structures in the VPS. Thevps_profile_present_flag[i] equal to 1 specifies that the profile andtier information is present in the i-th profile_tier_level( ) syntaxstructure. vps_profile_present_flag[lsIdx] equal to 0 specifies thatprofile and tier information is not present in the i-thprofile_tier_level( ) syntax structure and may be inferred for the i-thprofile_tier_level( ) syntax structure.

The parameter profile_ref_minus1[i] specifies that the profile and tierinformation for the i-th profile_tier_level( ) syntax structure may beinferred to be equal to the profile and tier information for the(profile_ref_minus1[i]+1)-th profile_tier_level( ) syntax structure. Thevalue of profile_ref_minus1[i]+1 may be less than i.

The parameter direct_dependency_flag[i][j] equal to 0 specifies that thelayer with index j is not a direct reference layer for the layer withindex i. direct_dependency_flag[i][j] equal to 1 specifies that thelayer with index j may be a direct reference layer for the layer withindex i. When direct_dependency_flag[i][j] is not present for i and j inthe range of 0 to vps_max_layers_minus1, it may be inferred to be equalto 0.

The variables NumDirectRefLayers[i] and RefLayerId[i][j] may be derivedas follows:

for(i=1; i<=vps_max_layers_minus1; i++)

-   -   for(j=0, NumDirectRefLayers[i]=0; j<i; j++)        -   if(direct_dependency_flag[i][j]==1)            -   RefLayerId[i][NumDirectRefLayers[i]++]=layer_id_in_nuh[j]                [END EXAMPLE A]

[START EXAMPLE B] The parameter vps_num_rep_formats specifies the numberof the following rep_format( ) syntax structures in the VPS. Thevps_rep_format_idx[i] specifies the index, into the set of rep_format( )syntax structures in the VPS, of the rep_format( ) syntax structure thatapplies to the layer with nuh_layer_id equal to layer_id_in_nuh[i]. Wheni is equal to 0 or vps_num_rep_formats is equal to 1, the value ofvps_rep_format_idx[i] may be inferred to be equal to 0. The value ofvps_rep_format_idx[i] may be in the range of 0 to vps_num_rep_formats−1,inclusive. [END EXAMPLE B]

[START EXAMPLE C] max_sub_layers_vps_predict_flag[i] equal to 1specifies that max_sub_layers_vps_minus1[i] may be inferred to be equalto max_sub_layers_vps_minus1[i−1] and thatsub_layer_vps_ordering_predict_flag[i] is present.max_sub_layers_vps_predict_flag[i] equal to 0 specifies thatmax_sub_layers_vps_minus1[i] is explicitly signalled. The value ofmax_sub_layers_vps_predict_flag[0] may be inferred to be equal to 0.

The parameter max_sub_layers_vps_minus1[i] is used for the inference ofthe SPS syntax element sps_max_sub_layers_minus1. Whenmax_sub_layers_vps_predict_flag[i] is equal to 1,max_sub_layers_vps_minus1[i] may be inferred to be equal tomax_sub_layers_vps_minus1[i−1]. The value ofmax_sub_layers_vps_minus1[i] may be inferred to be equal tovps_max_sub_layers_minus1. [END EXAMPLE C] [START EXAMPLE A]multiple_output_layer_sets_in_layer_set_flag equal to 1 specifies thatmore than one output layer set may be specified by the VPS for eachlayer set. multiple_output_layer_sets_in_layer_set_flag equal to 0specifies that only one output layer set is specified by the VPS foreach layer set, with the highest layer being the only target outputlayer. Accordingly, because multiple_output_layer_sets_in_layer_set_flagequal to 0 specifies that only one output layer set is specified by theVPS for each layer set, with the highest layer being the only targetoutput layer, no explicit signaling of target output layers for thedefault output layer sets is needed. For example, there is not need tosignal which layers are to be output because there is only one outputlayer set for each layer set.

The parameter num_output_layer_sets_minus1 plus 1 specifies the numberof output layer sets specified by the VPS. The value ofnum_output_layer_sets_minus1 may be in the range of 0 to 1023,inclusive. [END EXAMPLE A]

Alternatively, instead of num_output_layer_sets_minus1,num_addn_output_layer_sets which indicates the number of output layersets in addition to the vps_num_layers_sets_minus1+1 may be signalled.

[START EXAMPLE A] The parameter output_layer_set_idx_minus1[i] plus 1specifies the index of the layer set for the i-th output layer set. Thevalue of output_layer_set_idx_minus1[i] may be in the range of 0 tovps_num_layer_sets_minus1−1, inclusive. The length of theoutput_layer_set_idx_minus1[i] syntax element is Ceil(Log2(vps_num_layer_sets_minus1)) bits

output_layer_flag[i][j] equal to 1 specifies that the j-th layer in thelayer set is a target output layer of the i-th output layer set.output_layer_flag[i][j] equal to 0 specifies that the j-th layer in thelayer set is not a target output layer of the i-th output layer set.

The value of output_layer_flag[i][NumLayersInIdList[lsIdx] 1] may beinferred to be equal to 1, where lsIdx is equal tooutput_layer_set_idx_minus1[i]+1.

[END EXAMPLE A]

Alternatively, the value ofoutput_layer_flag[i][NumLayersInIdList[lsIdx]−1] may be inferred to beequal to 1, where lsIdx is equal to output_layer_set_idx_minus1[i]+1 andi is in the range of 0 to vps_num_layer_sets_minus1, inclusive and thevalue of output_layer_flag[i][j] may be inferred to be equal to 0 for iin the range of 0 to vps_num_layer_sets_minus1, inclusive, and j in therange of 0 to NumLayerIdInList[lsIdx]−2, inclusive and lsIdx is equal tooutput_layer_set_idx_minus1[i]+1.

[START EXAMPLE A] The parameter profile_level_tier_idx[i] specifies theindex, into the set of profile_tier_level( ) syntax structures in theVPS, of the profile_tier_level( ) syntax structure that applies to i-thoutput layer set. The length of the profile_level_tier_idx[i] syntaxelement may be Ceil(Log 2(vps_num_profile_tier_level_minus1+1)) bits.The value of profile_level_tier_idx[0] may be inferred to be equal to 0.The value of profile_level_tier_idx[i] may be in the range of 0 tovps_num_profile_tier_level_minus1, inclusive. [END EXAMPLE A]

[START EXAMPLE F] The parameter vps_num_other_sps_params specifies thenumber of the following other_sps_parameters( ) syntax structures in theVPS. The value of vps_num_other_sps_params may be in the range of 0 to15, inclusive. [END EXAMPLE F]

[START EXAMPLE D] The parameter vps_num_st_rps_candidates specifies thenumber of the following short_term_rps_candidates( ) syntax structuresin the VPS. The value of vps_num_st_rps_candidates may be in the rangeof 0 to 15, inclusive.

[END EXAMPLE D]

[START EXAMPLE E] The parameter vps_num_vui_params specifies the numberof the following vui_parameters( ) syntax structures in the VPS. Thevalue of vps_num_vui_params may be in the range of 0 to 15, inclusive.[END EXAMPLE E]

[START EXAMPLE F] vps_other_sps_params_idx[i] specifies the index, intothe set of other_sps_parameters( ) syntax structures in the VPS, of theother_sps_parameters( ) syntax structure that applies to the layer withnuh_layer_id equal to layer_id_in_nuh[i]. The length of thevps_other_sps_params_idx[i] syntax element may be Ceil(Log2(vps_num_other_sps_params)) bits. When vps_num_other_sps_params isequal to 1, the value of vps_other_sps_params_idx[i] may be inferred tobe equal to 0. The value of vps_other_sps_params_idx[i] may be in therange of 0 to vps_num_other_sps_params−1, inclusive. [END EXAMPLE F]

[START EXAMPLE D] The parameter vps_st_rps_idx[i] specifies the index,into the set of short_term_rps_candidates( ) syntax structures in theVPS, of the short_term_rps_candidates( ) syntax structure that appliesto the layer with nuh_layer_id equal to layer_id_in_nuh[i]. The lengthof the vps_st_rps_idx[i] syntax element may be Ceil(Log2(vps_num_st_rps_candidates)) bits. When vps_num_st_rps_candidates isequal to 1, the value of vps_st_rps_idx[i] may be inferred to be equalto 0. The value of vps_st_rps_idx[i] may be in the range of 0 tovps_num_st_rps_candidates−1, inclusive. [END EXAMPLE D]

[START EXAMPLE E] The parameter vps_vui_params_idx[i] specifies theindex, into the set of vui_parameters( ) syntax structures in the VPS,of the vui_parameters( ) syntax structure that applies to the layer withnuh_layer_id equal to layer_id_in_nuh[i]. The length of thevps_vui_params_idx[i] syntax element may be Ceil(Log2(vps_num_vui_params)) bits. When vps_num_vui_params is equal to 1, thevalue of vps_vui_params_idx[i] may be inferred to be equal to 0. Thevalue of vps_vui_params_idx[i] may be in the range of 0 tovps_num_vui_params−1, inclusive. [END EXAMPLE E]

[START EXAMPLE C] The variable MaxSubLayers[setId] for setId in therange of 0 to num_output_layer_sets−1, inclusive, is derived as follows:

for( setId = 0; setId < num_output_layer_sets; setId++ ) {  lsIdx =outptut_layer_set_idx_minus1[ setId ] + 1 // Layer set index highestLayerId = LayerSetLayerIdList[ lsIdx ][ NumLayersInIdList[ lsIdx] − 1 ]  MaxSubLayers[ setId ] = ( max_sub_layers_vps_minus1[ highestLayerId ] + 1) }

The parameter max_sub_layers_vps_predict_flag[i] equal to 1 specifiesthat max_sub_layers_vps_minus1[i] may be inferred to be equal tomax_sub_layers_vps_minus1[i−1] and thatsub_layer_vps_ordering_predict_flag[i] is present.max_sub_layers_vps_predict_flag[i] equal to 0 specifies thatmax_sub_layers_vps_minus1[i] is explicitly signalled. The value ofmax_sub_layers_vps_predict_flag[0] may be inferred to be equal to 0.

The parameter sub_layer_vps_buf_info_predict_flag[i] equal to 1specifies that max_vps_dec_pic_buffering_minus1[i][j] may be inferred tobe equal to max_vps_dec_pic_buffering_minus1[i−1][j] for each value ofj. sub_layer_vps_buf_info_predict_flag[i] equal to 0 specifies thatmax_vps_dec_pic_buffering_minus1[i][j] for at least one value of j isexplicitly signalled.

The parameter sub_layer_vps_buf_info_present_flag[i] equal to 1specifies that max_vps_dec_pic_buffering_minus1[i][j] are present forMaxSubLayers[i] sub-layers. sub_layer_vps_buf_info_present_flag[i] equalto 0 specifies that the values ofmax_vps_dec_pic_buffering_minus1[i][MaxSubLayers[i]−1] apply to allsub-layers.

The parameter max_vps_dec_pic_buffering_minus1[i][j] are used forinference of the values of the SPS syntax elementssps_max_dec_pic_buffering_minus1[j]. Whenmax_vps_dec_pic_buffering_minus1[i][j] is not present for i in the rangeof 0 to MaxSubLayers[i]−2, inclusive, due tosub_layer_vps_buf_info_present_flag[i] being equal to 0, it may beinferred to be equal tomax_vps_dec_pic_buffering_minus1[i][MaxSubLayers[i] 1].

The value of max_vps_dec_pic_buffering_minus1[0][j] for each value of jmay be inferred to be equal to vps_max_dec_pic_buffering_minus1[j].

The parameter sub_layer_vps_ordering_info_predict_flag[i] equal to 1specifies that the syntax elementssub_layer_vps_ordering_info_present_flag[i],max_vps_num_reorder_pics[i][j], and max_vps_latency_increase_plus1[i][j]are inferred to be equal tosub_layer_vps_ordering_info_present_flag[i−1],max_vps_num_reorder_pics[i−1][j], andmax_vps_latency_increase_plus1[i−1][j], respectively.sub_layer_vps_ordering_info_predict_flag[i] equal to 0 indicates thatthe syntax elements sub_layer_vps_ordering_info_present_flag[i],max_vps_num_reorder_pics[i][j], and max_vps_latency_increase_plus1[i][j]are explicitly signalled. When not present, the value ofsub_layer_vps_ordering_info_predict_flag[i] is set equal to 0.

The parameter sub_layer_vps_ordering_info_present_flag[i] equal to 1specifies that max_vps_num_reorder_pics[i][j] andmax_vps_latency_increase_plus1[i][j] are present formax_sub_layers_vps_minus1+1 sub-layers.sub_layer_vps_ordering_info_present_flag[i] equal to 0 specifies thatthe values of max_vps_num_reorder_pics[i][vps_max_sub_layers_minus1] andmax_vps_latency_increase_plus1[i][max_sub_layers_vps_minus1] apply toall sub-layers.

The parameter max_vps_num_reorder_pics[i][j] is used for inference ofthe values of the SPS syntax element sps_max_num_reorder_pics[j]. Whenmax_vps_num_reorder_pics[i][j] is not present for i in the range of 0 tomax_sub_layers_vps_minus1[i] 1, inclusive, due tosub_layer_vps_ordering_info_present_flag[i] being equal to 0, it may beinferred to be equal tomax_vps_num_reorder_pics[i][max_sub_layers_vps_minus1[i]].

The parameter max_vps_latency_increase_plus1[i][j] is used for inferenceof the values of the SPS syntax elementssps_max_latency_increase_plus1[j]. Whenmax_vps_latency_increase_plus1[i][j] is not present for i in the rangeof 0 to max_sub_layers_vps_minus1[i] 1, inclusive, due tosub_layer_vps_ordering_info_present_flag[i] being equal to 0, it may beinferred to be equal tomax_vps_latency_increase_plus1[i][max_sub_layers_vps_minus1[i]].

[END EXAMPLE C]

[START EXAMPLE B]

Table 5 illustrates an example of a representative format and semantics.

TABLE 5 Representation format syntax and semantics rep_format( ) {Descriptor chroma_format_vps_idc u(2) if( chroma_format_vps_idc = = 3 )  separate_colour_plane_vps_flag u(1) pic_width_vps_in_luma_samplesu(16) pic_height_vps_in_luma_samples u(16) bit_depth_vps_luma_minus8u(3) bit_depth_vps_chroma_minus8 u(3) }

The parameter chroma_format_vps_idc, separate_colour_plane_vps_flag,pic_width_vps_in_luma_samples, pic_height_vps_in_luma_samples,bit_depth_vps_luma_minus8, and bit_depth_vps_chroma_minus8 may be usedfor inference of the values of the SPS syntax elementschroma_format_idc, separate_colour_plane_flag,pic_width_in_luma_samples, pic_height_in_luma_samples,bit_depth_luma_minus8, and bit_depth_chroma_minus8, respectively, foreach SPS that refers to the VPS. For each of these syntax elements, allconstraints, if any, that apply to the value of the corresponding SPSsyntax element also apply. [END EXAMPLE B] Representation formatinformation may generally include bit depth, chroma sampling format,resolution of the sequences, for example. As illustrated in the exampleof Table 5, the representation format may include chroma_format_vps_idc,separate_colour_plane_vps_flag, pic_width_vps_in_luma_samples,pic_height_vps_in_luma_samples, bit_depth_vps_luma_minus8, andbit_depth_vps_chroma_minus8. Furthermore, as illustrated in Table 5,signaling of representation format in the VPS may be performed such thatthe representation format, e.g., chroma_format_vps_idc,separate_colour_plane_vps_flag, pic_width_vps_in_luma_samples,pic_height_vps_in_luma_samples, bit_depth_vps_luma_minus8, andbit_depth_vps_chroma_minus8, is accessible without entropy decoding. Inother words, as illustrated in Table 5, chroma_format_vps_idc,separate_colour_plane_vps_flag, pic_width_vps_in_luma_samples,pic_height_vps_in_luma_samples, bit_depth_vps_luma_minus8, andbit_depth_vps_chroma_minus8 are not entropy coded, i.e., the descriptorsare not ue(v). In some examples, each layer may be associated with aparticular representation format.

[START EXAMPLE F] Table 6 illustrates an example of other SPS parameterssyntax and semnantics.

TABLE 6 Other SPS parameters syntax and semantics other_sps_parameters() { Descriptor   conformance_window_vps_flag u(1)   if(conformance_window_vps_flag ) {     conf_win_vps_left_offset ue(v)    conf_win_vps_right_offset ue(v)     conf_win_vps_top_offset ue(v)    conf_win_vps_bottom_offset ue(v)   }  log2_vps_max_pic_order_cnt_lsb_minus4 ue(v)  log2_vps_min_luma_coding_block_size_minus3 ue(v)  log2_vps_diff_max_min_luma_coding_block_size ue(v)  log2_vps_min_transform_block_size_minus2 ue(v)  log2_vps_diff_max_min_transform_block_size ue(v)  max_vps_transform_hierarchy_depth_inter ue(v)  max_vps_transform_hierarchy_depth_intra ue(v)  scaling_list_enabled_vps_flag u(1)   if( scaling_list_enabled_vps_flag)     sps_scaling_list_data_present_vps_flag u(1)     if(sps_scaling_list_data_present_vps_flag )       scaling_list_data( )   }  amp_enabled_vps_flag u(1)   sample_adaptive_offset_enabled_vps_flagu(1)   pcm_enabled_vps_flag u(1)   if( pcm_enabled_vps_flag ) {    pcm_vps_sample_bit_depth_luma_minus1 u(4)    pcm_vps_sample_bit_depth_chroma_minus1 u(4)    log2_vps_min_pcm_luma_coding_block_size_minus3 ue(v)    log2_vps_diff_max_min_pcm_luma_coding_block_size ue(v)    pcm_vps_loop_filter_disabled_flag u(1)   }  long_term_ref_pics_present_vps_flag u(1)   if(long_term_ref_pics_present_vps_flag ) {     num_long_term_ref_pics_vpsue(v)     for( i = 0; i < num_long_term_ref_pics_vps; i++ ) {      lt_ref_pic_poc_lsb_vps[ i ] u(v)      used_by_curr_pic_lt_vps_flag[ i ] u(1)     }   }  temporal_mvp_enabled_vps_flag u(1)  strong_intra_smoothing_enabled_vps_flag u(1) }

For each of the syntax elements below, all constraints, if any, thatapply to the value of the corresponding SPS syntax element also apply:conformance_window_vps_flag, conf_win_vps_left_offset,conf_win_vps_right_offset, conf_win_vps_top_offset,conf_win_vps_bottom_offset, log 2_vps_max_pic_order_cnt_lsb_minus4, log2_vps_min_luma_coding_block_size_minus3, log2_vps_diff_max_min_luma_coding_block_size, log2_vps_min_transform_block_size_minus2, log2_vps_diff_max_min_transform_block_size,max_vps_transform_hierarchy_depth_inter,max_vps_transform_hierarchy_depth_intra, scaling_list_enabled_vps_flag,sps_scaling_list_data_present_vps_flag, amp_enabled_vps_flag,sample_adaptive_offset_enabled_vps_flag, pcm_enabled_vps_flag,pcm_vps_sample_bit_depth_luma_minus1,pcm_vps_sample_bit_depth_chroma_minus1, log2_vps_min_pcm_luma_coding_block_size_minus3, log2_vps_diff_max_min_pcm_luma_coding_block_size,pcm_vps_loop_filter_disabled_flag, long_term_ref_pics_present_vps_flag,num_long_term_ref_pics_vps, lt_ref_pic_poc_lsb_vps[i],used_by_curr_pic_lt_vps_flag[i], temporal_mvp_enabled_vps_flag, andstrong_intra_smoothing_enabled_vps_flag may be used for inference of thevalues of the SPS syntax elements conformance_window_flag,conf_win_left_offset, conf_win_right_offset, conf_win_top_offset,conf_win_bottom_offset, log 2_max_pic_order_cnt_lsb_minus4, log2_min_luma_coding_block_size_minus3, log2_diff_max_min_luma_coding_block_size, log2_min_transform_block_size_minus2, log2_diff_max_min_transform_block_size,max_transform_hierarchy_depth_inter,max_transform_hierarchy_depth_intra, scaling_list_enabled_flag,sps_scaling_list_data_present_flag, amp_enabled_flag,sample_adaptive_offset_enabled_flag, pcm_enabled_flag,pcm_sample_bit_depth_luma_minus1, pcm_sample_bit_depth_chroma_minus1,log 2_min_pcm_luma_coding_block_size_minus3, log2_diff_max_min_pcm_luma_coding_block_size,pcm_loop_filter_disabled_flag, long_term_ref_pics_present_flag,num_long_term_ref_pics_sps, lt_ref_pic_poc_lsb_sps[i],used_by_curr_pic_lt_flag[i], sps_temporal_mvp_enabled_flag, andstrong_intra_smoothing_enabled_flag, respectively. [END EXAMPLE F]

[START EXAMPLE D] Table 7 illustrates an example of short-term RPScandidates syntax and semantics.

TABLE 7 Short-term RPS candidates syntax and semanticsshort_term_rps_candidates( inferenceEnabledFlag ) { Descriptor  num_short_term_ref_pic_sets ue(v)   if( inferenceEnabledFlag )    pred_st_rps_cand_idx_plus1 u(v)   for( i = 0; i <num_short_term_ref_pic_sets; i++) {     if( pred_st_rps_cand_idx_plus1 >0 )       pred_from_rps_cand_list_flag[ i ] u(1)     if(!pred_from_rps_cand_list_flag[ i ] )       short_term_ref_pic_set( i )    else       idx_in_rps_cand[ i ] ue(v)   } }

The parameter num_short_term_ref_pic_sets specifies the number of thefollowing short_term_ref_pic_set( ) syntax structures. The value ofnum_short_term_ref_pic_sets may be in the range of 0 to 64, inclusive.

NOTE 1—A decoder should allocate memory for a total number ofnum_short_term_ref_pic_sets+1 short_term_ref_pic_set( ) syntaxstructures since there may be a short_term_ref_pic_set( ) syntaxstructure directly signalled in the slice headers of a current picture.A short_term_ref_pic_set( ) syntax structure directly signalled in theslice headers of a current picture has an index equal tonum_short_term_ref_pic_sets.

The parameter pred_st_rps_cand_idx_plus1 minus 1 specifies the index,into the set of short_term_rps_candidates( ) syntax structures in theVPS, of the short_term_rps_candidates( ) syntax structure that is usedto infer at least one short_term_ref_pic_set( ) syntax structure of thecurrent short_term_rps_candidates( ) syntax structure. When not present,pred_st_rps_cand_idx_plus1 may be inferred to be equal to 0. The valueof pred_st_rps_cand_idx_plus1 may be in the range of 1 tovps_num_st_rps_candidates−1, inclusive.

Having the pred_from_rps_cand_list_flag[i] equal to 1 specifies the i-thshort_term_ref_pic_set( ) syntax structure of the currentshort_term_rps_candidates( ) syntax structure is not present and set tobe one of the short_term_ref_pic_set( ) syntax structures present inanother short_term_rps_candidates( ) syntax structure.pred_from_rps_cand_list_flag[i] equal to 0 specifies the i-thshort_term_ref_pic_set( ) syntax structure of the currentshort_term_rps_candidates( ) syntax structure is present. When notpresent, the value of pred_from_rps_cand_list_flag[i] may be inferred tobe equal to 0. [END EXAMPLE D]

Alternatively, pred_from_rps_cand_list_flag[i] equal to 1 specifies thatthe variables DeltaPocS0, DeltaPocS1, UsedByCurrPicS1, UsedByCurrPicS0,NumPositivePics, NumNegativePics, and NumDeltaPocs corresponding to thei-th short_ter_ref_pic_set( ) are derived to be equal to the variablesDeltaPocS0, DeltaPocS1, UsedByCurrPicS1, UsedByCurrPicS0,NumPositivePics, NumNegativePics, and NumDeltaPocs, respectively, thatcorrespond to another short_term_rps_candidates( ) structure.

[START EXAMPLE D] The parameter idx_in_rps_cand[i] specifies the index,into the set of short_term_ref_pic_set( ) syntax structures of the(pred_st_rps_cand_idx_plus1−1)-th short_term_rps_candidates( ) syntaxstructure in the VPS, of the short_term_ref_pic_set( ) syntax structurethat is identical to the i-th short_term_ref_pic_set( ) syntax structureof the current short_term_rps_candidates( ).

When pred_from_rps_cand_list_flag[i] is equal to 1, the i-thshort_term_ref_pic_set( ) syntax structure in the currentshort_term_rps_candidates( ) syntax structure is set to be the same asthe idx_in_rps_cand[i]-th short_term_ref_pic_set( ) syntax structure ofthe (pred_st_rps_cand_idx_plus1−1)-th short_term_rps_candidates( )syntax structure in the VPS. [END EXAMPLE D]

Alternatively, when pred_from_rps_cand_list_flag[i] is equal to 1, thevariables DeltaPocS0, DeltaPocS1, UsedByCurrPicS1, UsedByCurrPicS0,NumPositivePics, NumNegativePics, and NumDeltaPocs corresponding to thei-th short_term_ref_pic_set( ) syntax structure in the currentshort_term_rps_candidates( ) syntax structure is set to be equal to thevariables DeltaPocS0, DeltaPocS1, UsedByCurrPicS1, UsedByCurrPicS0,NumPositivePics, NumNegativePics, and NumDeltaPocs, respectively, thatcorrespond to the idx_in_rps_cand[i]-th short_term_ref_pic_set( ) syntaxstructure of the (pred_st_rps_cand_idx_plus1−1)-thshort_term_rps_candidates( ) syntax structure in the VPS. Table 8illustrates an example of VUI parameters syntax and semantics.

TABLE 8 VUI parameters syntax and semantics vui_parameters( [STARTEXAMPLE E] timingParamsPresentFlag ) { Descriptor [START EXAMPLEE]  vui_parameters_present_flag u(1)   if( vui_parameters_present_flag ){ [END EXAMPLE E]     aspect_ratio_info_present_flag u(1)     if(aspect_ratio_info_present_flag ) {       aspect_ratio_idc u(8)       if(aspect_ratio_idc = = EXTENDED_SAR ) {         sar_width u(16)        sar_height u(16)       }     }     overscan_info_present_flagu(1)     if( overscan_info_present_flag )      overscan_appropriate_flag u(1)     video_signal_type_present_flagu(1)     if( video_signal_type_present_flag ) {       video_format u(3)      video_full_range_flag u(1)       colour_description_present_flagu(1)       if( colour_description_present_flag ) {        colour_primaries u(8)         transfer_characteristics u(8)        matrix_coeffs u(8)       }     }    chroma_loc_info_present_flag u(1)     if(chroma_loc_info_present_flag ) {       chroma_sample_loc_type_top_fieldue(v)       chroma_sample_loc_type_bottom_field ue(v)     }    neutral_chroma_indication_flag u(1)     field_seq_flag u(1)    frame_field_info_present_flag u(1)     default_display_window_flagu(1)     if( default_display_window_flag ) {      def_disp_win_left_offset ue(v)       def_disp_win_right_offsetue(v)       def_disp_win_top_offset ue(v)      def_disp_win_bottom_offset ue(v)     } [START EXAMPLE E]  if(timingParamsPresentFlag ) { [END EXAMPLE E]      vui_timing_info_present_flag u(1)       if(vui_timing_info_present_flag ) {         vui_num_units_in_tick u(32)        vui_time_scale u(32)         vui_poc_proportional_to_timing_flagu(1)         if( vui_poc_proportional_to_timing_flag )          vui_num_ticks_poc_diff_one_minus1 ue(v)        vui_hrd_parameters_present_flag u(1)         if(vui_hrd_parameters_present_flag )           hrd_parameters( 1,sps_max_sub_layers_minus1 )       } [START EXAMPLE E]    } [END EXAMPLEE]     bitstream_restriction_flag u(1)     if(bitstream_restriction_flag ) {       tiles_fixed_structure_flag u(1)      motion_vectors_over_pic_boundaries_flag u(1)      restricted_ref_pic_lists_flag u(1)      min_spatial_segmentation_idc ue(v)       max_bytes_per_pic_denomue(v)       max_bits_per_min_cu_denom ue(v)      log2_max_mv_length_horizontal ue(v)      log2_max_mv_length_vertical ue(v)     } [START EXAMPLE E]  } [ENDEXAMPLE E] }

[START EXAMPLE E] When timingParamsPresentFlag is equal to 0, thefollowing applies: The values of vui_timing_info_present_flag,vui_num_units_in_tick, vui_time_scale,vui_poc_proportional_to_timing_flag, andvui_num_ticks_poc_diff_one_minus1 are inferred to be equal tovps_timing_info_present_flag, vps_num_units_in_tick, vps_time_scale,vps_poc_proportional_to_timing_flag, andvps_num_ticks_poc_diff_one_minus1, respectively. The value ofvui_hrd_parameters_present_flag may be inferred to be equal to 0.

The parameter vui_parameters_present_flag equal to 1 specifies thatthere are more syntax elements in the vui_parameters( ) syntaxstructure. vui_parameters_present_flag equal to 0 specifies that thereis no more syntax elements in the vui_parameters( ) syntax structure . .. . [END EXAMPLE E]

In one example, as can be seen in Tables 8, visual signal information(e.g., video_format, video_full_range_flag, colour_primaries,transfer_characteristics, matrix_coeffs) is a subset of the VUIparameters. Further, as illustrated in the example of Table 4 the VUI,and hence the visual signal information, is in the VPS. By combining theinformation from Table 4 and Table 8 it is shown that the visual signalinformation is signalled per layer in the VPS.

Table 9 illustrates an example sequence parameter set RBSP syntax andsemantics.

TABLE 9 Sequence parameter set RBSP syntax and semanticsseq_parameter_set_rbsp( ) { Descriptor sps_video_parameter_set_id u(4)[START EXAMPLE F]  if( nuh_layer_id > 0 )  inherit_sps_params_from_vps_flag u(1) if(!inherit_sps_params_from_vps_flag ) { [END EXAMPLE F]  sps_max_sub_layers_minus1 u(3)   sps_temporal_id_nesting_flag u(1)[START EXAMPLE F]  } [END EXAMPLE F] if( nuh_layer_id = = 0 )  profile_tier_level( 1, sps_max_sub_layers_minus1 )sps_seq_parameter_set_id ue(v) [START EXAMPLE B]  if( nuh_layer_id = = 0) { [END EXAMPLE B]   chroma_format_idc ue(v)   if( chroma_format_idc == 3 )     separate_colour_plane_flag u(1)   pic_width_in_luma_samplesue(v)   pic_height_in_luma_samples ue(v) [START EXAMPLE B]  } [ENDEXAMPLE B] [START EXAMPLE F]  if( !inherit_sps_params_from_vps_flag ) {[END EXAMPLE F]     conformance_window_flag u(1)     if(conformance_window_flag ) {       conf_win_left_offset ue(v)      conf_win_right_offset ue(v)       conf_win_top_offset ue(v)      conf_win_bottom_offset ue(v)     } [START EXAMPLE F]  } [ENDEXAMPLE F] [START EXAMPLE B]  if( nuh_layer_id = = 0 ) { [END EXAMPLE B]    bit_depth_luma_minus8 ue(v)     bit_depth_chroma_minus8 ue(v) [STARTEXAMPLE B]  } [END EXAMPLE B] [START EXAMPLE F]  if(!inherit_sps_params_from_vps_flag ) { [END EXAMPLE F]    log2_max_pic_order_cnt_lsb_minus4 ue(v)    sps_sub_layer_ordering_info_present_flag u(1)     for( i = (sps_sub_layer_ordering_info_present_flag ? 0 : sps_max_sub_layers_minus1);         i <= sps_max_sub_layers_minus1; i++ ) {      sps_max_dec_pic_buffering_minus1[ i ] ue(v)      sps_max_num_reorder_pics[ i ] ue(v)      sps_max_latency_increase_plus1[ i ] ue(v)     }    log2_min_luma_coding_block_size_minus3 ue(v)    log2_diff_max_min_luma_coding_block_size ue(v)    log2_min_transform_block_size_minus2 ue(v)    log2_diff_max_min_transform_block_size ue(v)    max_transform_hierarchy_depth_inter ue(v)    max_transform_hierarchy_depth_intra ue(v)    scaling_list_enabled_flag u(1)     if( scaling_list_enabled_flag ) {      sps_scaling_list_data_present_flag u(1)       if(sps_scaling_list_data_present_flag )         scaling_list_data( )     }    amp_enabled_flag u(1)     sample_adaptive_offset_enabled_flag u(1)    pcm_enabled_flag u(1)     if( pcm_enabled_flag ) {      pcm_sample_bit_depth_luma_minus1 u(4)      pcm_sample_bit_depth_chroma_minus1 u(4)      log2_min_pcm_luma_coding_block_size_minus3 ue(v)      log2_diff_max_min_pcm_luma_coding_block_size ue(v)      pcm_loop_filter_disabled_flag u(1)     } [START EXAMPLED]    short_term_rps_candidates( 0 )  [removed:  num_short_term_ref_pic_sets] [removed:ue (v)]  [removed:   for( i = 0;i < num_short_term_ref_pic_sets; i++)]  [removed:    short_term_ref_pic_set( i )] [END EXAMPLE D]    long_term_ref_pics_present_flag u(1)     if(long_term_ref_pics_present_flag ) {       num_long_term_ref_pics_spsue(v)       for( i = 0; i < num_long_term_ref_pics_sps; i++ ) {        lt_ref_pic_poc_lsb_sps[ i ] u(v)        used_by_curr_pic_lt_sps_flag[ i ] u(1)       }     }    sps_temporal_mvp_enabled_flag u(1)    strong_intra_smoothing_enabled_flag u(1) [START EXAMPLE E][removed:vui_parameters_present_flag] [removed:u (1)] [remove:   if(vui_parameters_present_flag )][END EXAMPLE E]     vui_parameters( [STARTEXAMPLE E] nuh_layer_id = = 0 [END EXAMPLE E] ) [START EXAMPLE F]  }[END EXAMPLE F]   sps_extension_flag u(1)   if( sps_extension_flag ) {    sps_extension( )     sps_extension2_flag u(1)     if(sps_extension2_flag )       while( more_rbsp_data( ) )        sps_extension_data_flag u(1)   }   rbsp_trailing_bits( ) }

[START EXAMPLE B]

When nuh_layer_id of the SPS is equal to 0, the values ofchroma_format_idc, separate_colour_plane_flag,pie_width_in_luma_samples, pic_height_in_luma_samples,bit_depth_luma_minus8, and bit_depth_chroma_minus8 may be equal tochroma_format_vps_idc, separate_colour_plane_vps_flag,pic_width_vps_in_luma_samples, pic_height_vps_in_luma_samples,bit_depth_vps_luma_minus8, and bit_depth_vps_chroma_minus8,respectively, of the 0-th rep_format( ) syntax structure in the activeVPS.

For each layer with nuh_layer_id greater than 0 that refers to the SPS,let layerIdx be set equal to the value for whichlayer_id_in_nuh[layerIdx] is equal to the nuh_layer_id of the layer, thefollowing applies: [END EXAMPLE B]

[START EXAMPLE A] When nuh_layer_id of the SPS is equal to 0, theprofile_tier_level( ) syntax structure in the SPS is ignored. [ENDEXAMPLE A]

As illustrated in Table 8 and Table 9, no timing information issignalled in an SPS VUI, e.g., for any layer greater than layer 0.

[START EXAMPLE B] The values of chroma_format_idc,separate_colour_plane_flag, pic_width_in_luma_samples,pic_height_in_luma_samples, bit_depth_luma_minus8, andbit_depth_chroma_minus8 are inferred to be equal tochroma_format_vps_idc, separate_colour_plane_vps_flag,pic_width_vps_in_luma_samples, pic_height_vps_in_luma_samples,bit_depth_vps_luma_minus8, and bit_depth_vps_chroma_minus8,respectively, of the vps_rep_format_idx[layerIdx]-th rep_format( )syntax structure in the active VPS, regardless of whether these syntaxelements are present in the VPS. [END EXAMPLE B]

[START EXAMPLE F] The parameterinherit_sps_params_from_vps_flag equal to1 specifies that, for the SPS RBSP, the values of all syntax elementsand syntax structures until the syntax element sps_extension_flag, otherthan the syntax elements sps_video_parameter_set_id andsps_seq_parameter_set_id, may be inherited from the active VPS.inherit_sps_params_from_vps_flag equal to 0 specifies that these valuesare not inherited from the active VPS. When not present, the value ofinherit_sps_params_from_vps_flag may be inferred to be equal to 0. Whenvps_num_rep_fromats, vps_num_other_sps_params,vps_num_st_rps_candidates, or vps_num_vui_params is equal to 0, thevalue of inherit_sps_params_from_vps_flag may be equal to 0. Wheninherit_sps_params_from_vps_flag is equal to 1, the following applies:[END EXAMPLE F]

[START EXAMPLE C] The value of sps_max_sub_layers_minus1 for each layerthat refers to the SPS may be inferred to be equal tomax_sub_layers_vps_minus1[layerIdx] where layerIdx is equal to the valuefor which layer_id_in_nuh[layerIdx] is equal to the nuh_layer_id of thelayer.

The values of sps_max_dec_pic_buffering_minus1[i] for each layer thatrefers to the SPS may be inferred to be equal tomax_vps_dec_pic_buffering_minus1[lsIdx][i] for i in the range of 0 toMaxSubLayers[lxIdx] 1, inclusive, where lsIdx is in the range of 0 tovps_num_layer_sets_minus1, inclusive, and denotes the index, into theset of output layer sets that is specified by the VPS, of the outputlayer set for which the layer is the highest layer and the only targetoutput layer.

The values of sps_max_num_reorder_pics[i], andsps_max_latency_increase_plus1[i] for each layer that refers to the SPSare inferred to be equal to max_vps_num_reorder_pics[layerIdx][i] andmax_vps_latency_increase_plus1[layerIdx][i], where layerIdx is equal tothe value for which layer_id_in_nuh[layerIdx] is equal to thenuh_layer_id of the layer, for i in the range of 0 tosps_max_sub_layers_minus1, inclusive. The value ofsps_temporal_id_nesting_flag for each layer that refers to the SPS maybe inferred to be equal to vps_temporal_id_nesting_flag. [END EXAMPLE C]

As can be seen from the above discussion and Table 9, some examples donot signal sps_max_sub_layers_minus1 and sps_temporal_id_nesting_flagwhen nuh_layer_id_(—)>0.

[START EXAMPLE F] The values of conformance_window_flag,conf_win_left_offset, conf_win_right_offset, conf_win_top_offset,conf_win_bottom_offset, log 2_max_pic_order_cnt_lsb_minus4, log2_min_luma_coding_block_size_minus3, log2_diff_max_min_luma_coding_block_size, log2_min_transform_block_size_minus2, log2_diff_max_min_transform_block_size,max_transform_hierarchy_depth_inter,max_transform_hierarchy_depth_intra, scaling_list_enabled_flag,sps_scaling_list_data_present_flag, amp_enabled_flag,sample_adaptive_offset_enabled_flag, pcm_enabled_flag,pcm_sample_bit_depth_luma_minus1, pcm_sample_bit_depth_chroma_minus1,log 2_min_pcm_luma_coding_block_size_minus3, log2_diff_max_min_pcm_luma_coding_block_size,pcm_loop_filter_disabled_flag, long_term_ref_pics_present_flag,num_long_term_ref_pics_sps, lt_ref_pic_poc_lsb_sps[i],used_by_curr_pic_lt_flag[i], sps_temporal_mvp_enabled_flag, andstrong_intra_smoothing_enabled_flag for each layer that refers to theSPS are inferred to be equal to conformance_window_vps_flag,conf_win_vps_left_offset, conf_win_vps_right_offset,conf_win_vps_top_offset, conf_win_vps_bottom_offset, log2_vps_max_pic_order_cnt_lsb_minus4, log2_vps_min_luma_coding_block_size_minus3, log2_vps_diff_max_min_luma_coding_block_size, log2_vps_min_transform_block_size_minus2, log2_vps_diff_max_min_transform_block_size,max_vps_transform_hierarchy_depth_inter,max_vps_transform_hierarchy_depth_intra, scaling_list_enabled_vps_flag,sps_scaling_list_data_present_vps_flag, amp_enabled_vps_flag,sample_adaptive_offset_enabled_vps_flag, pcm_enabled_vps_flag,pcm_vps_sample_bit_depth_luma_minus1,pcm_vps_sample_bit_depth_chroma_minus1, log2_vps_min_pcm_luma_coding_block_size_minus3, log2_vps_diff_max_min_pcm_luma_coding_block_size,pcm_vps_loop_filter_disabled_flag, long_term_ref_pics_present_vps_flag,num_long_term_ref_pics_vps, lt_ref_pic_poc_lsb_vps[i],used_by_curr_pic_lt_vps_flag[i], temporal_mvp_enabled_vps_flag, andstrong_intra_smoothing_enabled_vps_flag, respectively, of thevps_other_sps_params_idx[layerIdx]-th other_sps_parameters( ) syntaxstructure in the active VPS, where layerIdx is equal to the value forwhich layer_id_in_nuh[layerIdx] is equal to the nuh_layer_id of thelayer.

When sps_scaling_list_data_present_vps_flag is equal to 1, the value ofthe syntax structure scaling_list_data( ) for each layer that refers tothe SPS may be inferred to be equal to the syntax structurescaling_list_data( ) in the vps_other_sps_params_idx[layerIdx]-thother_sps_parameters( ) syntax structure in the active VPS, wherelayerIdx is equal to the value for which layer_id_in_nuh[layerIdx] maybe equal to the nuh_layer_id of the layer. [END EXAMPLE F]

[START EXAMPLE D] The value of the syntax strucutureshort_term_rps_candidates( ) for each layer that refers to the SPS maybe inferred to be equal to the vps_st_rps_idx[layerIdx]-thshort_term_rps_candidates( ) syntax structure in the active VPS, wherelayerIdx is equal to the value for which layer_id_in_nuh[layerIdx] isequal to the nuh_layer_id of the layer. [END EXAMPLE D]

[START EXAMPLE E] In some examples, the value of the syntax strucuturevui_parameters( ) for each layer that refers to the SPS may be inferredto be equal to the vps vui_params_idx[layerIdx]-th vui_parameters( )syntax strucuture in the active VPS, where layerIdx is equal to thevalue for which layer_id_in_nuh[layerIdx] is equal to the nuh_layer_idof the layer. [END EXAMPLE E]

. . .

The parameter conf_win_left_offset, conf_win_right_offset,conf_win_top_offset, and conf_win_bottom_offset specify the samples ofthe pictures in the coded video stream (CVS) that are output from thedecoding process, in terms of a rectangular region specified in picturecoordinates for output. When [START EXAMPLE F]inherit_sps_params_from_vps_flag is equal to 0 and [END EXAMPLE F]conformance_window_flag is equal to 0, the values ofconf_win_left_offset, conf_win_right_offset, conf_win_top_offset, andconf_win_bottom_offset may be inferred to be equal to 0.

The conformance cropping window contains the luma samples withhorizontal picture coordinates from SubWidthC*conf_win_left_offset topic_width_in_luma_samples−(SubWidthC*conf_win_right_offset+1) andvertical picture coordinates from SubHeightC*conf_win_top_offset topic_height_in_luma_samples−(SubHeightC*conf_win_bottom_offset+1),inclusive.

The value of SubWidthC*(conf_win_left_offset+conf_win_right_offset) maybe be less than pic_width_in_luma_samples, and the value ofSubHeightC*(conf_win_top_offset+conf_win_bottom_offset) may be less thanpic_height_in_luma_samples.

When ChromaArrayType is not equal to 0, the corresponding specifiedsamples of the two chroma arrays are the samples having picturecoordinates (x/SubWidthC, y/SubHeightC), where (x, y) are the picturecoordinates of the specified luma samples.

NOTE 3 The conformance cropping window offset parameters are onlyapplied at the output. All internal decoding processes are applied tothe uncropped picture size.

. . .

The parameter sps_sub_layer_ordering_info_present_flag equal to 1 [STARTEXAMPLE C], when inherit_sps_params_from_vps_flag is equal to 0, [ENDEXAMPLE C] specifies that sps_max_dec_pic_buffering_minus1[i],sps_max_num_reorder_pics[i], and sps_max_latency_increase_plus1[i] arepresent for sps_max_sub_layers_minus1+1 sub-layers.sps_sub_layer_ordering_info_present_flag equal to 0 [START EXAMPLE C],when inherit_sps_params_from_vps_flag is equal to 0, [END EXAMPLE C]specifies that the values ofsps_max_dec_pic_buffering_minus1[sps_max_sub_layers_minus1],sps_max_num_reorder_pics[sps_max_sub_layers_minus1], andsps_max_latency_increase_plus1[sps_max_sub_layers_minus1] apply to allsub-layers.

The parameter sps_max_dec_pic_buffering_minus1[i] plus 1 specifies themaximum required size of the decoded picture buffer for the CVS in unitsof picture storage buffers when HighestTid is equal to i. In someexamples, the value of sps_max_dec_pic_buffering_minus1[i] may be in therange of 0 to MaxDpbSize−1 (as specified in subclause A.4), inclusive.When i is greater than 0, sps_max_dec_pic_buffering_minus1[i] may be begreater than or equal to sps_max_dec_pic_buffering_minus1[i−1]. Thevalue of sps_max_dec_pic_buffering_minus1[i] may be less than or equalto vps_max_dec_pic_buffering_minus1[i] for each value of i. When [STARTEXAMPLE C] inherit_sps_params_from_vps_flag is equal to 0 and [ENDEXAMPLE C] sps_max_dec_pic_buffering_minus1[i] is not present for i inthe range of 0 to sps_max_sub_layers_minus1−1, inclusive, due tosps_sub_layer_ordering_info_present_flag being equal to 0, it may beinferred to be equal tosps_max_dec_pic_buffering_minus1[sps_max_sub_layers_minus1].

The parameter sps_max_num_reorder_pics[i] indicates the maximum allowednumber of pictures that can precede any picture in the CVS in decodingorder and follow that picture in output order when HighestTid is equalto i. The value of sps_max_num_reorder_pics[i] may be in the range of 0to sps_max_dec_pic_buffering_minus1[i], inclusive. When i is greaterthan 0, sps_max_num_reorder_pics[i] may be greater than or equal tosps_max_num_reorder_pics[i−1]. The value of sps_max_num_reorder_pics[i]may be less than or equal to vps_max_num_reorder_pics[i] for each valueof i. When [START EXAMPLE C] inherit_sps_params_from_vps_flag is equalto 0 and [END EXAMPLE C] sps_max_num_reorder_pics[i] is not present fori in the range of 0 to sps_max_sub_layers_minus1−1, inclusive, due tosps_sub_layer_ordering_info_present_flag being equal to 0, it may beinferred to be equal tosps_max_num_reorder_pics[sps_max_sub_layers_minus1].

The parameter sps_max_latency_increase_plus1[i] not equal to 0 is usedto compute the value of SpsMaxLatencyPictures[i], which specifies themaximum number of pictures that can precede any picture in the CVS inoutput order and follow that picture in decoding order when HighestTidis equal to i.

When sps_max_latency_increase_plus1[i] is not equal to 0, the value ofSpsMaxLatencyPictures[i] is specified as follows:SpsMaxLatencyPictures[i]=sps_max_num_reorder_pics[i]+(7-9)

-   -   sps_max_latency_increase_plus1[i]−1

When sps_max_latency_increase_plus1[i] is equal to 0, no correspondinglimit is expressed. In some examples, the value ofsps_max_latency_increase_plus1[i] may be in the range of 0 to 232−2,inclusive. In some examples, when vps_max_latency_increase_plus1[i] isnot equal to 0, the value of sps_max_latency_increase_plus1[i] may notbe equal to 0 and may be less than or equal tovps_max_latency_increase_plus1[i] for each value of i. When [STARTEXAMPLE C] inherit_sps_params_from_vps_flag is equal to 0 and [ENDEXAMPLE C] sps_max_latency_increase_plus1[i] is not present for i in therange of 0 to sps_max_sub_layers_minus1−1, inclusive, due tosps_sub_layer_ordering_info_present_flag being equal to 0, it may beinferred to be equal tosps_max_latency_increase_plus1[sps_max_sub_layers_minus1].

. . .

The parameter sps_scaling_list_data_present_flag equal to 1 specifiesthat scaling list data are present in the SPS [START EXAMPLE F] orinherited from the active VPS [END EXAMPLE F]. In some examples,sps_scaling_list_data_present_flag equal to 0 specifies that scalinglist data are not present in the SPS [START EXAMPLE F] and not inheritedfrom the active VPS [END EXAMPLE F]. When [START EXAMPLE F]inherit_sps_params_from_vps_flag is equal to 0 andsps_scaling_list_data_present_flag [END EXAMPLE F] is not present, thevalue of sps_scaling_list_data_present_flag may be inferred to be equalto 0. When scaling_list_enabled_flag is equal to 1 andsps_scaling_list_data_present_flag is equal to 0, the default scalinglist data are used to derive the array ScalingFactor as described in thescaling list data semantics specified in subclause 7.4.5 of the HEVCstandard.

The parameter pcm_loop_filter_disabled_flag specifies whether the loopfilter process is disabled on reconstructed samples in a coding unitwith pcm_flag equal to 1 as follow: If pcm_loop_filter_disabled_flag isequal to 1, the deblocking filter and sample adaptive offset filterprocesses on the reconstructed samples in a coding unit with pcm_flagequal to 1 are disabled. Otherwise (pcm_loop_filter_disabled_flag valueis equal to 0), the deblocking filter and sample adaptive offset filterprocesses on the reconstructed samples in a coding unit with pcm_flagequal to 1 are not disabled.

When [START EXAMPLE F] inherit_sps_params_from_vps_flag is equal to 0and [END EXAMPLE F] pcm_loop_filter_disabled_flag is not present, it maybe inferred to be equal to 0.

[START EXAMPLE D] [removed:num_short_term_ref_pic_sets specifies thenumber of short_term_ref_pic_set( ) syntax structures included in theSPS. The value of num_short_term_ref_pic_sets shall be in the range of 0to 64, inclusive.]

[removed: NOTE 5—A decoder should allocate memory for a total number ofnum_short_term_ref_pic_sets+1 short_term_ref_pic_set( ) syntaxstructures since there may be a short_term_ref_pic_set( ) syntaxstructure directly signalled in the slice headers of a current picture.A short_term_ref_pic_set( ) syntax structure directly signalled in theslice headers of a current picture has an index equal tonum_short_term_ref_pic_sets.] [END EXAMPLE D]

. . .

The parameter lt_ref_pic_poc_lsb_sps[i] specifies the picture ordercount modulo MaxPicOrderCntLsb of the i-th candidate long-term referencepicture specified [START EXAMPLE F] by [remove:in] [END EXAMPLE F] theSPS. The number of bits used to represent lt_ref_pic_poc_lsb_sps[i] isequal to log 2_max_pic_order_cnt_lsb_minus4+4.

The parameter used_by_curr_pic_lt_sps_flag[i] equal to 0 specifies thatthe i-th candidate long-term reference picture specified [START EXAMPLEF] by [remove:in] [END EXAMPLE F] the SPS is not used for reference by apicture that includes in its long-term RPS the i-th candidate long-termreference picture specified [START EXAMPLE F] by [remove:in] [ENDEXAMPLE F] the SPS.

. . .

[START EXAMPLE E] [removed: vui_parameters_present_flag equal to 1specifies that the vui_parameters( ) syntax structure as specified inAnnex E is present. vui_parameters_present_flag equal to 0 specifiesthat the vui_parameters( ) syntax structure as specified in Annex E isnot present.] [END EXAMPLE E]

FIG. 4 is a flowchart illustrating an example method for decoding videodata in accordance with the systems and methods described herein. In theillustrated example of FIG. 4, a video decoder 30 may receive anon-entropy encoded set of profile, tier, and level syntax structures(402). The non-entropy encoded set of profile, tier, and level syntaxstructures may be at a position within a VPS extension prior to syntaxelements of the VPS extension that are entropy encoded.

Video decoder 30 may refer to one of the profile, tier, and level syntaxstructures for each of a plurality of output layer sets (404) and decodevideo data of one of the output layer sets based on information from theprofile, tier, and level syntax structure referred to for the outputlayer set (406). For example, video decoder 30 may ignore an outputlayer set if the profile, tier, and level of the bitstream of the outputlayer set indicate that a higher capability than the decoding capabilityof video decoder 30, as indicated by the decoder's profile, tier, andlevel, is needed for decoding of the bitstream. When the requireddecoding capability, as indicated by the profile, tier, and level of thebitstream of the output layer set, is not higher than the decodingcapability of video decoder 30, video decoder 30 decodes the bitstreamof the output layer set using the required decoding processes asindicated by the profile, tier, and level of the bitstream.

In some examples, video decoder 30 may receive an SPS with anuh_layer_id equal to 0, wherein the SPS includes a profile, tier, andlevel syntax structure for a layer of video data.

In some examples, video decoder 30 may receive an output layer flag [i][j] that, when equal to 1, specifies that a j-th layer in the layer setis a target output layer of an i-th output layer set, and, when equal to0, specifies that the j-th layer in the layer set is not the targetoutput layer of the i-th output layer set. For example, video encoder 20may transmit an output layer flag [i] [j] that, when equal to 1,specifies that a j-th layer in the layer set is a target output layer ofan i-th output layer set, and, when equal to 0, specifies that the j-thlayer in the layer set is not the target output layer of the i-th outputlayer set. Video decoder 30 may transmit an output layer flag [i] [j]that, when equal to 1, specifies that a j-th layer in the layer set is atarget output layer of an i-th output layer set, and, when equal to 0,specifies that the j-th layer in the layer set is not the target outputlayer of the i-th output layer set.

Video decoder 30 may also generate the output layer set based on theoutput layer flag [i] [j]. For example, video encoder 20 may also encodethe output layer set based on the output layer flag [i] [j].

FIG. 5 is a flowchart illustrating an example method for encoding videodata in accordance with the systems and methods described herein. In theillustrated example of FIG. 5, video encoder 20 may generate an outputlayer set based on the output layer flag [i] [j]. For example, videoencoder 20 may refer to one of the profile, tier, and level syntaxstructures for each of a plurality of output layer sets (502). Videoencoder 20 may also encode the output layer set based on the outputlayer flag [i] [j] (504).

Video encoder 20 may encode a VPS with VPS extension having anon-entropy encoded set of profile, tier, and level syntax structures(506). In some examples, video encoder 20 may transmit, store, or causeto be stored the VPS and VPS extension having a non-entropy encoded setof profile, tier, and level syntax structures. The non-entropy encodedset of profile, tier, and level syntax structures may be at a positionwithin a VPS extension prior to syntax elements of the VPS extensionthat are entropy encoded. For example, video encoder 20 may encode videodata according to a profile, tier, level that is selected. Video encoder20 may also encode the profilel, tier, level syntax in the VPS for useby the decoder.

In some examples, video encoder 20 may encode an SPS with a nuh_layer_idequal to 0, wherein the SPS includes a profile, tier, and level syntaxstructure for a layer of video data. For example, video encoder 20 maysend an SPS with a nuh_layer_id equal to 0, wherein the SPS includes aprofile, tier, and level syntax structure for a layer of video data.When an SPS with nuh_layer_id equal to 0 is referred by a layer withnuh_layer_id greater than 0, the profile_tier_level( ) syntax structurein the SPS is not applied for that layer.

Accordingly, as can be seen above, each layer needs to refer to an SPS.Conventionally, any two layers that are of different values of spatialresolutions, bit depths, or color formats have to refer to two differentSPSs as these representation format parameters are signalled in the SPS.However, when these parameters for all SPSs except those withnuh_layer_id equal to 0 are moved to the VPS, and when it is specifiedthat the representation format parameters in an SPS with nuh_layer_idequal to 0 that is referred to by a layer with nuh_layer_id greater than0 are ignored, it is possible for layers with different values ofspatial resolutions, bit depths, or color formats to refer to the sameSPSs. In other words, according to some embodiments of this disclosure,layers with different values of spatial resolutions, bit depths, orcolor formats can share the same SPS, as long as other SPS parametersrequired for the layers are the same.

In some examples, video encoder 20 may transmit an output layer flag [i][j] that, when equal to 1, specifies that a j-th layer in the layer setis a target output layer of an i-th output layer set, and, when equal to0, specifies that the j-th layer in the layer set is not the targetoutput layer of the i-th output layer set. For examples, video encoder20 may transmit an output layer flag [i] [j] that, when equal to 1,specifies that a j-th layer in the layer set is a target output layer ofan i-th output layer set, and, when equal to 0, specifies that the j-thlayer in the layer set is not the target output layer of the i-th outputlayer set.

FIG. 6 is a flowchart illustrating an example method for decoding videodata in accordance with the systems and methods described herein. In theillustrated example of FIG. 6, a video decoder 30 may receive anon-entropy encoded layer dependency information at a position within aVPS extension prior to syntax elements of the VPS extension that areentropy encoded (602).

Video decoder 30 may decode the non-entropy encoded layer dependencyinformation before an entropy encoded syntax element (604). In anexample, video decoder 30 may decode the non-entropy encoded layerdependency information before any entropy encoded syntax element.

Video decoder 30 may decode video data of one or more of the layers ofvideo data based on the non-entropy encoded layer dependency information(606). The layer dependency information may indicate whether one of thelayers is a direct reference layer for another of the layers. In someexamples, when the layer dependency information indicates whether one ofthe layers is a direct reference layer for another of the layers, thelayer dependency information may also indicate which one of the layersis a direct reference layer for another of the layers. In other words,the layer dependency information may indicate whether one of the layersis a direct reference layer for another of the layers and identify theone of the layers that is a direct reference layer for another of thelayers. In some examples, the layer dependency information includes adirect_dependency_flag[i][j] that, when equal to 0, specifies that alayer with index j is not a direct reference layer for a layer withindex i, and when equal to 1, specifies that the layer with index j maybe a direct reference layer for the layer with index i. When decoding apicture, video decoder 30 may derive an inter-layer reference pictureset based on the layer dependency information, among other information,and may further derive a reference picture list based on the inter-layerreference picture set, among other information, and then may decode thepicture using inter-layer prediction from a picture in a directreference layer.

FIG. 7 is a flowchart illustrating an example method for encoding videodata in accordance with the systems and methods described herein. Videoencoder 20 may encode video data of one or more of the layers of videodata based on a non-entropy encoded layer dependency information (702).Video encoder 20 may encode a non-entropy encoded layer dependencyinformation at a position within a video parameter set (VPS) extensionprior to syntax elements of the VPS extension that are entropy encoded(704). For example, video encoder 20 may encode video data of one ormore of the layers of video data based on the non-entropy encoded layerdependency information. The layer dependency information may indicatewhether one of the layers is a direct reference layer for another of thelayers. In some examples, video encoder 20 may transmit, store, or causeto be stored a non-entropy encoded layer dependency information at aposition within a video parameter set (VPS) extension prior to syntaxelements of the VPS extension that are entropy encoded.

In some examples, the layer dependency information includes adirect_dependency_flag[i][j] that, when equal to 0, specifies that alayer with index j is not a direct reference layer for a layer withindex i, and when equal to 1, specifies that the layer with index j maybe a direct reference layer for the layer with index i.

FIG. 8 is a flowchart illustrating an example method for decoding videodata in accordance with the systems and methods described herein. In theexample of FIG. 8, more than one output layer set may be signalled forone layer set. Accordingly, if more than one output layer set issignalled for one layer set a video decoder 30, e.g., by way of inputinterface 28, may receive a first output layer set for a layer set(802). Video decoder 30 may also receive a second output layer set forthe layer set (804). Furthermore, while the example of FIG. 8illustrates two output layer set for one layer set, it will beunderstood that three, four, or even more output layer sets may besignalled for a layer set. Video decoder 30 may decode video data for atleast one of the first output layer set and the second output layer set(806).

FIG. 9 is a flowchart illustrating an example method for encoding videodata in accordance with the systems and methods described herein. In theexample of FIG. 9, more than one output layer set may be signalled forone layer set. Accordingly, video encoder 20 may encode video data forat least one of a first output layer set and a second output layer set(902). Accordingly, output interface 22 may transmit encoded data fromvideo encoder 20. The data transmitted may include the first outputlayer set for a layer set (904) and the second output layer set for thelayer set (906). In some examples, output interface 22 may transmit thedata to input interface 28. In other examples, output interface 22 maytransmit the data to storage device 34 for storage.

FIG. 10 is a flowchart illustrating an example method for decoding videodata in accordance with the systems and methods described herein. Theexample of FIG. 10 illustrates signaling of representation format in theVPS, potentially in a way that it is accessible without entropydecoding. In other words, a representation format in the VPS is notentropy encoded. It may, for example, be fixed length coded.Accordingly, video decoder 30 may receive a non-entropy encodedrepresentation format within a VPS, e.g., through input interface 28(1002). The representation format may include one or more of chromaformat, whether different colour planes are separately coded, picturewidth, picture height, luma bit depth, and chroma bit depth. Videodecoder 30 may also decode video data based on the non-entropy encodedrepresentation format within the VPS (1004). Because the representationformat is in the VPS potentially in a way that it is accessible withoutentropy decoding devices that do not perform entropy coding may haveaccess to the representation format, for example, in some cases a MediaAware Network Entities (MANEs) may not have an entropy coding device.Video decoder 30 may decode representation format in the VPS,potentially without entropy decoding in accordance with the techniquesof this disclosure, and each layer may be associated with a particularrepresentation format.

FIG. 11 is a flowchart illustrating an example method for encoding videodata in accordance with the systems and methods described herein. Theexample of FIG. 11 illustrates signaling of representation format in theVPS, potentially in a way that it is accessible without entropydecoding. In other words, a representation format in the VPS is notentropy encoded. It may be, for example, fixed length coded.Accordingly, video encoder 20 may encode video data based on thenon-entropy encoded representation format within the VPS (1102). Therepresentation format may include one or more of chroma format, whetherdifferent colour planes are separately coded, picture width, pictureheight, luma bit depth, and chroma bit depth. Video encoder 20 maytransmit a non-entropy encoded representation format within a VPS(1104). Video encoder 20 may encode representation format in the VPS, ina way that is accessible without entropy decoding in accordance with thetechniques of this disclosure, and each layer may be associated with aparticular representation format.

FIG. 12 is a flowchart illustrating an example method for encoding videodata in accordance with the systems and methods described herein. Theexample of FIG. 12 illustrates signaling of visual signal information,e.g., video_format, video_full_range_flag, colour_primaries,transfer_characteristics, matrix_coeffs, per layer in the VPS.Accordingly, video decoder 30 may receive a VPS including a series oflayers, each layer including visual signal information (1002). Videodecoder 30 may also decode video data based on the received visualsignal information signalled per layer in the VPS.

FIG. 13 is a flowchart illustrating an example method for encoding videodata in accordance with the systems and methods described herein. Theexample of FIG. 13 illustrates signaling of visual signal information,e.g., video_format, video_full_range_flag, colour_primaries,transfer_characteristics, matrix_coeffs, per layer in the VPS.Accordingly, video encoder 20 may encode video data based on thereceived visual signal information signalled per layer in the VPS(1302). Video encoder 20 may transmit the VPS including a series oflayers, each layer including visual signal information for each of aseries of layers (1304).

In one or more examples, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over, as oneor more instructions or code, a computer-readable medium and executed bya hardware-based processing unit. Computer-readable media may includecomputer-readable storage media, which corresponds to a tangible mediumsuch as data storage media, or communication media including any mediumthat facilitates transfer of a computer program from one place toanother, e.g., according to a communication protocol. In this manner,computer-readable media generally may correspond to (1) tangiblecomputer-readable storage media which is non-transitory or (2) acommunication medium such as a signal or carrier wave. Data storagemedia may be any available media that can be accessed by one or morecomputers or one or more processors to retrieve instructions, codeand/or data structures for implementation of the techniques described inthis disclosure. A computer program product may include acomputer-readable medium.

By way of example, and not limitation, such computer-readable storagemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage, or other magnetic storage devices, flashmemory, or any other medium that can be used to store desired programcode in the form of instructions or data structures and that can beaccessed by a computer. Also, any connection is properly termed acomputer-readable medium. For example, if instructions are transmittedfrom a website, server, or other remote source using a coaxial cable,fiber optic cable, twisted pair, digital subscriber line (DSL), orwireless technologies such as infrared, radio, and microwave, then thecoaxial cable, fiber optic cable, twisted pair, DSL, or wirelesstechnologies such as infrared, radio, and microwave are included in thedefinition of medium. It should be understood, however, thatcomputer-readable storage media and data storage media do not includeconnections, carrier waves, signals, or other transient media, but areinstead directed to non-transient, tangible storage media. Disk anddisc, as used herein, includes compact disc (CD), laser disc, opticaldisc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wheredisks usually reproduce data magnetically, while discs reproduce dataoptically with lasers. Combinations of the above should also be includedwithin the scope of computer-readable media.

Instructions may be executed by one or more processors, such as one ormore digital signal processors (DSPs), general purpose microprocessors,application specific integrated circuits (ASICs), field programmablelogic arrays (FPGAs), or other equivalent integrated or discrete logiccircuitry. Accordingly, the term “processor,” as used herein may referto any of the foregoing structure or any other structure suitable forimplementation of the techniques described herein. In addition, in someaspects, the functionality described herein may be provided withindedicated hardware and/or software modules configured for encoding anddecoding, or incorporated in a combined codec. Also, the techniquescould be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide varietyof devices or apparatuses, including a wireless handset, an integratedcircuit (IC) or a set of ICs (e.g., a chip set). Various components,modules, or units are described in this disclosure to emphasizefunctional aspects of devices configured to perform the disclosedtechniques, but do not necessarily require realization by differenthardware units. Rather, as described above, various units may becombined in a codec hardware unit or provided by a collection ofintraoperative hardware units, including one or more processors asdescribed above, in conjunction with suitable software and/or firmware.

Various examples have been described. These and other examples arewithin the scope of the following claims.

What is claimed is:
 1. A method of decoding multilayer video dataincluding layers of video data, the method comprising: receiving anon-entropy encoded layer dependency information at a position within avideo parameter set (VPS) extension prior to syntax elements of the VPSextension that are entropy encoded; decoding the non-entropy encodedlayer dependency information before an entropy encoded syntax element;and decoding video data of one or more of the layers of video data basedon the non-entropy encoded layer dependency information, wherein thelayer dependency information indicates whether one of the layers is adirect reference layer for another of the layers.
 2. The method of claim1, wherein the layer dependency information includes adirect_dependency_flag[i][j] that, when equal to 0, specifies that alayer with index j is not a direct reference layer for a layer withindex I, and when equal to 1, specifies that the layer with index j maybe a direct reference layer for the layer with index i.
 3. The method ofclaim 1, wherein the VPS extension further includes: avps_num_profile_tier_level_minus1 plus 1 syntax element that specifies anumber of profile_tier_level( ) syntax structures in the VPS; avps_profile_present_flag[i] that when equal to 1 specifies that theprofile and tier information is present in an i-th profile_tier_level( )syntax structure, and that when equal to 0 specifies that profile andtier information is not present in the i-th profile_tier_level( ) syntaxstructure and is inferred for the i-th profile_tier_level( ) syntaxstructure; and a profile_ref_minus1[i] syntax element that specifiesthat the profile and tier information for the i-th profile_tier_level( )syntax structure is inferred to be equal to profile and tier informationfor a (profile_ref_minus1[i]+1)-th profile_tier_level( ) syntaxstructure.
 4. The method of claim 1, wherein the VPS extension furtherincludes: a multiple_output_layer_sets_in_layer_set_flag that specifiesthat more than one output layer set may be specified by the VPS for eachlayer set and that only one output layer set is specified by the VPS foreach layer set, with a highest layer being an only target output layer,depending on a value of the multiple_output_layer_sets_in_layer_setflag;a num_output_layer_sets_minus1 plus 1 syntax element that specifies anumber of output layer sets specified by the VPS; anoutput_layer_set_idx_minus1[i] plus 1 syntax element that specifies anindex of the layer set for an i-th output layer set, wherein a length ofthe output_layer_set_idx_minus1[i] syntax element is Ceil(Log2(vps_num_layer_sets_minus1)) bits; an output_layer_flag[i][j] syntaxelement that specifies that a j-th layer in the layer set is a targetoutput layer of the i-th output layer set or that the j-th layer in thelayer set is not a target output layer of the i-th output layer set; anda profile_level_tier_idx[i] syntax element that specifies an index, intoa set of profile_tier_level( ) syntax structures in the VPS, of theprofile_tier_level( ) syntax structure that applies to i-th output layerset.
 5. The method of claim 1, wherein a value ofoutput_layer_flag[i][NumLayersInIdList[lsIdx]−1] is inferred to be equalto 1, where lsIdx is equal to output_layer_set_idx_minus1[i]+1, a valueof profile_level_tier_idx[0] is inferred to be equal to 0, and a lengthof the profile_level_tier_idx[i] syntax element is Ceil(Log2(vps_num_profile_tier_level_minus1+1)) bits.
 6. A method of encodingmultilayer video data including layers of video data, the methodcomprising: encoding video data of one or more of the layers of videodata based on a non-entropy encoded layer dependency information,wherein a layer dependency information indicates whether one of thelayers is a direct reference layer for another of the layers; andencoding the non-entropy encoded layer dependency information at aposition within a video parameter set (VPS) extension prior to syntaxelements of the VPS extension that are entropy encoded.
 7. The method ofclaim 6, wherein the layer dependency information includes adirect_dependency_flag[i][j] that, when equal to 0, specifies that alayer with index j is not a direct reference layer for a layer withindex I, and when equal to 1, specifies that the layer with index j maybe a direct reference layer for the layer with index i.
 8. The method ofclaim 6, wherein the layer dependency information includes: avps_num_profile_tier_level_minus1 plus 1 syntax element that specifies anumber of profile_tier_level( ) syntax structures in the VPS; avps_profile_present_flag[i] that when equal to 1 specifies that theprofile and tier information is present in an i-th profile_tier_level( )syntax structure, and that when equal to 0 specifies that profile andtier information is not present in the i-th profile_tier_level( ) syntaxstructure and is inferred for the i-th profile_tier_level( ) syntaxstructure; and a profile_ref_minus1[i] syntax element that specifiesthat the profile and tier information for the i-th profile_tier_level( )syntax structure is inferred to be equal to profile and tier informationfor a (profile_ref_minus1[i]+1)-th profile_tier_level( ) syntaxstructure.
 9. The method of claim 6, wherein the layer dependencyinformation includes: a multiple_output_layer_sets_in_layer_set_flagthat specifies that more than one output layer set may be specified bythe VPS for each layer set and that only one output layer set isspecified by the VPS for each layer set, with a highest layer being anonly target output layer, depending on a value of themultiple_output_layer_sets_in_layer_set_flag; anum_output_layer_sets_minus1 plus 1 syntax element that specifies anumber of output layer sets specified by the VPS; anoutput_layer_set_idx_minus1[i] plus 1 syntax element that specifies anindex of the layer set for an i-th output layer set, wherein a length ofthe output_layer_set_idx_minus1[i] syntax element is Ceil(Log2(vps_num_layer_sets_minus1)) bits; an output_layer_flag[i][j] syntaxelement that specifies that a j-th layer in the layer set is a targetoutput layer of the i-th output layer set or that the j-th layer in thelayer set is not a target output layer of the i-th output layer set; anda profile_level_tier_idx[i] syntax element that specifies an index, intoa set of profile_tier_level( ) syntax structures in the VPS, of theprofile_tier_level( ) syntax structure that applies to i-th output layerset.
 10. The method of claim 6, wherein a value ofoutput_layer_flag[i][NumLayersInIdList[lsIdx]−1] is inferred to be equalto 1, where lsIdx is equal to output_layer_set_idx_minus1[i]+1, a valueof profile_level_tier_idx[0] is inferred to be equal to 0, and a lengthof the profile_level_tier_idx[i] syntax element is Ceil(Log2(vps_num_profile_tier_level_minus1+1)) bits.
 11. An apparatus fordecoding video data comprising: a memory configured to store the videodata; and one or more processors configured to: receive a non-entropyencoded layer dependency information at a position within a videoparameter set (VPS) extension prior to syntax elements of the VPSextension that are entropy encoded; decode the non-entropy encoded layerdependency information before an entropy encoded syntax element; anddecode video data of one or more layers of video data based on thenon-entropy encoded layer dependency information, wherein the layerdependency information indicates whether one of the layers is a directreference layer for another of the layers.
 12. The apparatus of claim11, wherein the layer dependency information includes adirect_dependency_flag[i][j] that, when equal to 0, specifies that alayer with index j is not a direct reference layer for a layer withindex I, and when equal to 1, specifies that the layer with index j maybe a direct reference layer for the layer with index i.
 13. Theapparatus of claim 11, wherein the layer dependency informationincludes: a vps_num_profile_tier_level_minus1 plus 1 syntax element thatspecifies a number of profile_tier_level( ) syntax structures in theVPS; a vps_profile_present_flag[i] that when equal to 1 specifies thatthe profile and tier information is present in an i-thprofile_tier_level( ) syntax structure, and that when equal to 0specifies that profile and tier information is not present in the i-thprofile_tier_level( ) syntax structure and is inferred for the i-thprofile_tier_level( ) syntax structure; and a profile_ref_minus1[i]syntax element that specifies that the profile and tier information forthe i-th profile_tier_level( ) syntax structure is inferred to be equalto profile and tier information for a (profile_ref_minus1[i]+1)-thprofile_tier_level( ) syntax structure.
 14. The apparatus of claim 11,wherein the layer dependency information includes: amultiple_output_layer_sets_in_layer_set_flag that specifies that morethan one output layer set may be specified by the VPS for each layer setand that only one output layer set is specified by the VPS for eachlayer set, with a highest layer being an only target output layer,depending on a value of themultiple_output_layer_sets_in_layer_set_flag; anum_output_layer_sets_minus1 plus 1 syntax element that specifies anumber of output layer sets specified by the VPS; anoutput_layer_set_idx_minus1[i] plus 1 syntax element that specifies anindex of the layer set for an i-th output layer set, wherein a length ofthe output_layer_set_idx_minus1[i] syntax element is Ceil(Log2(vps_num_layer_sets_minus1)) bits; an output_layer_flag[i][j] syntaxelement that specifies that a j-th layer in the layer set is a targetoutput layer of the i-th output layer set or that the j-th layer in thelayer set is not a target output layer of the i-th output layer set; anda profile_level_tier_idx[i] syntax element specifies an index, into aset of profile_tier_level( ) syntax structures in the VPS, of theprofile_tier_level( ) syntax structure that applies to i-th output layerset.
 15. The apparatus of claim 11, wherein a value ofoutput_layer_flag[i][NumLayersInIdList[lsIdx]−1] is inferred to be equalto 1, where lsIdx is equal to output_layer_set_idx_minus1[i]+1, a valueof profile_level_tier_idx[0] is inferred to be equal to 0, and a lengthof the profile_level_tier_idx[i] syntax element is Ceil(Log2(vps_num_profile_tier_level_minus1+1)) bits.
 16. An apparatus forencoding video data comprising: a memory configured to store the videodata; and one or more processors configured to: encode video data of oneor more layers of video data based on a non-entropy encoded layerdependency information, wherein a layer dependency information indicateswhether one of the layers is a direct reference layer for another of thelayers; and encode the non-entropy encoded layer dependency informationat a position within a video parameter set (VPS) extension prior tosyntax elements of the VPS extension that are entropy encoded.
 17. Theapparatus of claim 16, wherein the layer dependency information includesa direct_dependency_flag[i][j] that, when equal to 0, specifies that alayer with index j is not a direct reference layer for a layer withindex I, and when equal to 1, specifies that the layer with index j maybe a direct reference layer for the layer with index i.
 18. Theapparatus of claim 16, wherein the layer dependency informationincludes: a vps_num_profile_tier_level_minus1 plus 1 syntax element thatspecifies a number of profile_tier_level( ) syntax structures in theVPS; a vps_profile_present_flag[i] that when equal to 1 specifies thatthe profile and tier information is present in an i-thprofile_tier_level( ) syntax structure, and that when equal to 0specifies that profile and tier information is not present in the i-thprofile_tier_level( ) syntax structure and is inferred for the i-thprofile_tier_level( ) syntax structure; and a profile_ref_minus1[i]syntax element that specifies that the profile and tier information forthe i-th profile_tier_level( ) syntax structure is inferred to be equalto profile and tier information for a (profile_ref_minus1[i]+1)-thprofile_tier_level( ) syntax structure.
 19. The apparatus of claim 16,wherein the layer dependency information includes: amultiple_output_layer_sets_in_layer_set_flag that specifies that morethan one output layer set may be specified by the VPS for each layer setand that only one output layer set is specified by the VPS for eachlayer set, with a highest layer being an only target output layer,depending on a value of themultiple_output_layer_sets_in_layer_set_flag; anum_output_layer_sets_minus1 plus 1 syntax element that specifies anumber of output layer sets specified by the VPS; anoutput_layer_set_idx_minus1[i] plus 1 syntax element that specifies anindex of the layer set for an i-th output layer set, wherein a length ofthe output_layer_set_idx_minus1[i] syntax element is Ceil(Log2(vps_num_layer_sets_minus1)) bits; an output_layer_flag[i][j] syntaxelement that specifies that a j-th layer in the layer set is a targetoutput layer of the i-th output layer set or that the j-th layer in thelayer set is not a target output layer of the i-th output layer set; anda profile_level_tier_idx[i] syntax element that specifies an index, intoa set of profile_tier_level( ) syntax structures in the VPS, of theprofile_tier_level( ) syntax structure that applies to i-th output layerset.
 20. The apparatus of claim 16, wherein a value ofoutput_layer_flag[i][NumLayersInIdList[lsIdx]−1] is inferred to be equalto 1, where lsIdx is equal to output_layer_set_idx_minus1[i]+1, a valueof profile_level_tier_idx[0] is inferred to be equal to 0, and a lengthof the profile_level_tier_idx[i] syntax element is Ceil(Log2(vps_num_profile_tier_level_minus1+1)) bits.
 21. An apparatus fordecoding multilayer video data including layers of video datacomprising: means for receiving a non-entropy encoded layer dependencyinformation at a position within a video parameter set (VPS) extensionprior to syntax elements of the VPS extension that are entropy encoded;means for decoding the non-entropy encoded layer dependency informationbefore an entropy encoded syntax element; and means for decoding videodata of one or more of the layers of video data based on the non-entropyencoded layer dependency information, wherein the layer dependencyinformation indicates whether one of the layers is a direct referencelayer for another of the layers.
 22. A non-transitory computer readablestorage medium storing instructions that upon execution by one or moreprocessors cause the one or more processors to: receive a non-entropyencoded layer dependency information at a position within a videoparameter set (VPS) extension prior to syntax elements of the VPSextension that are entropy encoded; decode the non-entropy encoded layerdependency information before an entropy encoded syntax element; anddecode video data of one or more layers of video data based on thenon-entropy encoded layer dependency information, wherein the layerdependency information indicates whether one of the layers is a directreference layer for another of the layers.